Abstract
Background
Sleep disturbance is a common condition in patients with schizophrenia. Studies have shown that insufficient sleep and excessive sleep lead to adverse health outcomes. This study aimed to identify the factors associated with short and long sleep duration, as well as the prevalence of somatic comorbidities in schizophrenia patients.
Methods
This study was conducted in 24 mental health institutes of Guangdong Province using a multistage-stratified and random sampling method. All information was collected by face-to-face interview with a structured questionnaire. The association of sleep duration with sociodemographic and clinical factors was determined using multinomial logistic regressions. Subgroup analysis was performed in the various source of patients.
Results
A total of 6 024 schizophrenia patients were enrolled in this study, among whom 8.6% (n = 521) reported short sleep duration and 47.2% (n = 2 850) had long sleep duration. The most common comorbid chronic diseases in the entire cohort were hypertension (8.0%), diabetes (6.8%) and hyperlipidemia (3.2%). Factors such as, current smoker, outpatients, benzodiazepines (BZDs), side effects, comorbidities, age of onset, and illness duration were positively associated with short sleep duration. On the other hand, personal annul income < 10 000 yuan, personal annul income ≥ 40 000 yuan, chronic patients, first-generation antipsychotics (FGAs) and side effects were positively associated with long sleep duration. In outpatient settings, overweight was associated with long sleep duration, whereas in inpatient settings, being female positively correlated with long sleep duration.
Conclusion
Disruption of sleep duration and somatic comorbidities are highly prevalent in patients with schizophrenia. This study demonstrates the complex relationships among socioeconomic information, clinical factors and sleep duration in schizophrenia, highlighting the need for developing targeted interventions and management strategies for sleep duration.
Clinical trial number
Not applicable.
Keywords: Schizophrenia, Sleep duration, Comorbidities, Outpatients
Introduction
Schizophrenia is a severe mental disorder manifesting as positive symptoms, negative symptoms and general psychopathology, with a lifetime prevalence of 0.6% in China [1]. From 1990 to 2019, the raw prevalence of schizophrenia increased from 14.2 million to 23.6 million, the incidence rose from 941,000 to 1.3 million, and disability-adjusted life years (DALYs) grew from 9.1 to 15.1 million, corresponding to an increase of over 65%, 37%, and 65%, respectively [2]. Approximately 60% of schizophrenia patients experience relapse within one year, increasing the risk of repeated or prolonged hospitalizations [3]. Clinical data indicate that the mortality rates of schizophrenia patients are higher compared to that of the general population, with the mortality gap tending to be static or increase over time [4].
Sleep is a fundamental process that plays a role in the maintenance of homeostasis, modulating processes such as endocrine, immune and cognitive functions. Therefore, adequate sleep duration is essential for the sustenance of normal physical and mental health as it allows the central nervous system to recover from daily exhaustion [5]. The National Sleep Foundation recommends 7 to 9 h per night for young adults and adults [6]. Notably, insufficient and excessive sleep are associated with adverse health outcomes, including obesity, hypertension, metabolic dysfunction and mental disorders [7, 8]. Systematic Reviews have reported U-shaped associations between sleep duration and all-cause mortality [9].
Patients with schizophrenia often present with sleep disturbance, which compromises their quality of life [10]. In patients with schizophrenia, homeostatic and circadian processes involved in sleep regulation are disrupted [11]. Compared with healthy controls, schizophrenia patients exhibit altered sleep architecture, including longer sleep latency, reduced sleep efficiency, increased night-time awakenings, decreased slow-wave sleep and latency of rapid eye movement sleep [12, 13]. Sleep deprivation may trigger psychosis-like symptoms in healthy individuals [14], underscoring the significance of sleep in the progression or recovery of mental disorders. Sleep disturbances in schizophrenia increase the incidence of thought disorders, psychotic symptoms [15], cognitive impairments [16], depressive symptoms [17], suicidality [18], and lead to poorer treatment compliance and outcomes [19]. Schizophrenia is associated with alterations in sleep spindle characteristics, which can be considered neurophysiological biomarkers of the condition [20]. A Mendelian randomization study uncovered that long sleep duration was correlated with increased risk of schizophrenia [21], suggesting the potential benefits of addressing sleep problems in the prevention of psychiatric disorders. Therefore, it is imperative to identify risk factors influencing sleep duration to guide the development of management strategies for schizophrenia patients. This study aimed to explore the prevalence and correlates of short and long sleep duration, as well as the prevalence of chronic comorbidities in patients with schizophrenia.
Methods
Study design and sample
This large-scale mental health survey was carried out by Guangdong Mental Health Center and designed to explore the use of essential medicines, medical insurance system and its coverage of essential medicines among the patients with severe mental disorder in Guangdong Province. In the Severe Mental Disorders Information Management System of Guangdong Province, there were about 500 000 register patients with severe mental disorders at the end of 2018, including 330 000 patients with schizophrenia. For the present study, an approximately proportional sample of 1/100 was sampled.
A multistage-stratified sampling method was adopted to recruit suitable participants. Initially, cluster sampling method was used to select prefecture-level cities and 11 prefecture-level cities were included. Secondly, in each prefecture-level city, 3 to 5 districts or counties were selected using the random sampling method. Thirdly, community-dwelling patients and inpatients in each selected district or county were chosen through the proportionally stratified random cluster sampling method. The study was performed in 24 mental health institutes from December 2018 to March 2019. Schizophrenia patients who met the 10th Revision of the International Classification of diseases (ICD-10) diagnostic criteria were deemed eligible for this survey. The investigation team comprised 926 professional members including psychiatrists, public health physicians, community psychiatric doctors, and nurses. The investigators collected the demographic and clinical information by face-to-face interview using a self-designed questionnaire. The details of the method adopted in this survey can be found in a previous study [22]. Patients under the age of 18 were excluded from this study. All procedures were performed in accordance with the Declaration of Helsinki. Moreover, the study protocol was approved by the Ethics Committee of Guangdong Provincial People’s Hospital (Ethics approval number: GDMHR2018201H). Informed consent to participate was obtained from the patients or their legal guardians.
Assessment
Demographic and clinical variables
The following sociodemographic data were collected: age range, gender (male/female), body mass index (BMI, kg/m2), education level (≤ 9 years, > 9 years), marital status (married/cohabitation, single/divorced/separated), personal annul income (CNY, < 10000, 10000–39999, ≥ 40000, 1 USD = 6.9196 CNY), current smoker (no, yes), current drinker (no, yes), and exercise (never, 1–3 times a month, 1–5 times a week, everyday).
The collected clinical information included age of onset, source of patients (inpatients, outpatients), state of disease (first episode, chronic patients), illness duration (months), side effects, comorbidities, use of first-generation antipsychotics (FGAs), second-generation antipsychotics (SGAs) and benzodiazepines (BZDs). The diagnosis of comorbidities in the past year was investigated using a self-report approach and based on diagnostic certificate provide by a secondary or above medical institution.
Sleep duration
The sleep duration included night sleep and daytime nap. Night sleep duration was determined by asking “In the past month, how many hours of sleep do you get per night on average (note: accurate to 15 minutes)”. The daytime nap duration was evaluated by asking “In the past month, how many hours did you sleep during daytime on average”. Given that sleeping 7 to 9 h per night was recommended by National Sleep Foundation to promote optimal health [6], we divided patients into three groups based on the sleep duration: <7 h (short sleepers), 7–9 h (medium sleepers), > 9 h (long sleepers).
Statistical analyses
The final analysis was performed on data derived from adult patients. All data analyses were performed with SPSS Complex Samples version 25.0 package (IBM SPSS, IBM Corp, Armonk, NY, USA). Categorical variables were presented as frequencies (%), whereas for continuous variables, the average was calculated and presented as mean and standard deviation (SD). Continuous variables that exhibited a normal distribution were analyzed with the Kolmogorov-Smirnov one-sample test. Categorical variables were compared between short, medium and long sleepers with Chi-square (X2) test, whereas continuous variables that followed a normal distribution were analyzed using one way ANOVA. Otherwise, nonparametric test (Kruskal-Wallis Test) was performed for continuous variables that did not follow a normal distribution. Multinomial logistic regression analyses were conducted to investigate the relationships between dependent variables and independent variables that exhibited significant differences in univariate analysis. In addition, multinomial logistic regression was conducted to determine the independent associations of short and long sleepers with various chronic diseases. Adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) were estimated to explore the association between sociodemographic and clinical variables and short sleep duration or long sleep duration. Differences were considered significant if P < 0.05 (two-tailed).
The collinearity of age, age of onset and illness duration were examined. Correlation analyses were conducted between potential confounders with Contingency correlation and Spearman’s correlation, including age range and comorbidities, gender and smoking, gender and drinking, income and education. To eliminate the effect of confounders, stratified analysis was performed among smoking and drinking by gender, and among FGAs, SGAs, BZDs, side effects and comorbidities by source of patients. Finally, subgroup analysis was conducted by the source of patients.
Results
Demographic and clinical features of schizophrenia patients
In total, 6 024 schizophrenia patients were included in the study with a mean age of 43.2 years (SD = 13.1) and 58.9% (n = 3 548) were male. The mean sleep duration of the schizophrenia patients in Guangdong Province was 9.3 h, being 9.4 h in males and 9.2 in females, indicating significant gender difference (P = 0.001). In the entire patient cohort, 8.6% (n = 521) reported short sleep duration, 44.0% (n = 2 653) reported medium sleep duration and 47.2% (n = 2 850) had long sleep duration.
Table 1 shows the basic demographic and clinical characteristics of schizophrenia patients. Notably, significant differences were observed between female and male patients in the percentage of participants with short (50.1% vs. 49.9%) and long (38.2% vs. 61.8%) sleep durations (X2 = 28.87, P < 0.001). Further analysis revealed that 23.5% (n = 1410) participants were overweight and 5.6% (n = 337) participants were obese. Among the participants, 23.7% (n = 1 405) had a high school education or higher, 38.9% (n = 2 332) had married or cohabitation status, 50.8% (n = 3 022) had personal annul income less than 10 000 yuan, 18.7% (n = 1 125) were current smokers, 5.1% (n = 309) were current drinkers, and 59.8% (n = 3 589) never exercised.
Table 1.
Demographic and clinical characteristics of the participants (n = 6024)
| Variables | Total (n = 6024) | Short Sleepers (n = 521) | Medium Sleepers (n = 2653) | Long Sleepers (n = 2850) | Statistics | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | X 2 | P | |
| Age, years (n = 6024) | 138.69 | < 0.001 | ||||||||
| 18–34 | 1777 | 29.5 | 99 | 19.0 | 704 | 26.5 | 974 | 34.2 | ||
| 35–44 | 1465 | 24.3 | 93 | 17.9 | 651 | 24.5 | 721 | 25.3 | ||
| 45–54 | 1492 | 24.8 | 151 | 29.0 | 674 | 25.4 | 667 | 23.4 | ||
| 55–64 | 898 | 14.9 | 132 | 25.3 | 422 | 47.0 | 344 | 12.1 | ||
| ≥ 65 | 392 | 6.5 | 46 | 8.8 | 202 | 7.6 | 144 | 5.1 | ||
| Gender (n = 6024) | 28.87 | < 0.001 | ||||||||
| Male | 3548 | 58.9 | 260 | 49.9 | 1528 | 57.6 | 1760 | 61.8 | ||
| Female | 2476 | 41.1 | 261 | 50.1 | 1125 | 42.4 | 1090 | 38.2 | ||
| BMI, kg/m2 (n = 5993) | 7.23 | 0.30 | ||||||||
| < 18.5 | 573 | 9.6 | 53 | 10.2 | 230 | 8.7 | 290 | 10.3 | ||
| 18.5 ≤ BMI < 25 | 3673 | 61.3 | 315 | 60.6 | 1656 | 62.6 | 1702 | 60.2 | ||
| 25 ≤ BMI < 30 | 1410 | 23.5 | 123 | 23.7 | 624 | 23.6 | 663 | 23.5 | ||
| ≥ 30 | 337 | 5.6 | 29 | 5.6 | 136 | 5.1 | 172 | 6.1 | ||
| Education level (n = 5927) | 15.35 | < 0.001 | ||||||||
| > 9 years | 1405 | 23.7 | 135 | 26.1 | 670 | 25.7 | 600 | 21.4 | ||
| ≤ 9 years | 4522 | 76.3 | 383 | 73.9 | 1938 | 74.3 | 2201 | 78.6 | ||
| Marital status (n = 5991) | 73.65 | < 0.001 | ||||||||
| Married/Cohabitation | 2332 | 38.9 | 274 | 52.6 | 1090 | 41.3 | 968 | 34.2 | ||
| Single/Divorced/Separated | 3659 | 61.1 | 247 | 47.4 | 1550 | 58.7 | 1862 | 65.8 | ||
| Personal annul income, yuan (n = 5945) | 43.12 | < 0.001 | ||||||||
| < 10,000 | 3022 | 50.8 | 252 | 49.1 | 1243 | 47.3 | 1527 | 54.4 | ||
| 10,000–39,999 | 2136 | 35.9 | 215 | 41.9 | 1016 | 38.7 | 905 | 32.3 | ||
| ≥ 40,000 | 787 | 13.2 | 46 | 9.0 | 367 | 14.0 | 374 | 13.3 | ||
| Current smoker (n = 6016) | 9.00 | 0.01 | ||||||||
| No | 4891 | 81.3 | 400 | 76.8 | 2150 | 81.1 | 2341 | 82.3 | ||
| Yes | 1125 | 18.7 | 121 | 23.2 | 501 | 18.9 | 503 | 17.7 | ||
| Current drinker (n = 6024) | 2.75 | 0.25 | ||||||||
| No | 5715 | 94.9 | 492 | 94.4 | 2505 | 94.4 | 2718 | 95.4 | ||
| Yes | 309 | 5.1 | 29 | 5.6 | 148 | 5.6 | 132 | 4.6 | ||
| Exercise (n = 6001) | 68.87 | < 0.001 | ||||||||
| Never | 3589 | 59.8 | 326 | 62.9 | 1456 | 55.1 | 1807 | 63.6 | ||
| 1–3 times/month | 793 | 13.2 | 46 | 8.9 | 397 | 15.0 | 359 | 12.3 | ||
| 1–5 times/week | 949 | 15.8 | 75 | 14.5 | 504 | 19.1 | 370 | 13.0 | ||
| Everyday | 670 | 11.1 | 71 | 13.7 | 284 | 10.8 | 315 | 11.1 | ||
| Source of patients (n = 5960) | 139.68 | < 0.001 | ||||||||
| Inpatient | 2684 | 45.0 | 148 | 28.5 | 1068 | 40.5 | 1468 | 52.3 | ||
| Outpatient | 3276 | 55.0 | 372 | 71.5 | 1567 | 59.5 | 1337 | 47.7 | ||
| State of disease (n = 5953) | 8.29 | 0.01 | ||||||||
| First episode | 125 | 2.1 | 19 | 3.7 | 58 | 2.2 | 48 | 1.7 | ||
| Chronic patients | 5828 | 97.9 | 501 | 96.3 | 2572 | 97.8 | 2755 | 98.3 | ||
| FGAs (n = 6024) | 1929 | 32.0 | 152 | 29.2 | 725 | 27.3 | 1052 | 36.9 | 60.11 | < 0.001 |
| SGAs (n = 6024) | 5212 | 86.5 | 419 | 80.4 | 2290 | 86.3 | 2503 | 87.8 | 20.86 | < 0.001 |
| BZDs (n = 6024) | 1502 | 24.9 | 143 | 27.4 | 620 | 23.4 | 739 | 25.9 | 6.73 | 0.03 |
| Side effects (n = 5156) | 1790 | 34.7 | 166 | 38.4 | 656 | 29.7 | 968 | 38.5 | 43.24 | < 0.001 |
| Comorbidities (n = 5731) | 1397 | 24.4 | 163 | 34.1 | 617 | 24.5 | 617 | 22.6 | 29.34 | < 0.001 |
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | H | P | |
| Age of onset, years (n = 6005) | 27.33 | 10.88 | 30.34 | 12.15 | 28.20 | 10.96 | 25.99 | 10.36 | 106.21 | < 0.001 |
| Illness duration, months (n = 6023) | 194.97 | 134.11 | 218.06 | 147.47 | 195.02 | 135.65 | 190.95 | 129.75 | 14.17 | 0.001 |
BMI, Body Mass Index (kg/m2); BZD, benzodiazepine; FGA, first-generation antipsychotic; SGA, second-generation antipsychotic
The mean age of onset was 27.3 years and the mean illness duration was 194.9 months. In the entire cohort, 45.0% (n = 2 684) of the participants were inpatients. The usage rate of FGAs, SGAs and BZDs were 32.0%, 86.5% and 24.9%, respectively. Moreover, 34.7% (n = 1 790) and 24.4% (n = 1 397) participants reported side effects and comorbidities, respectively.
Table 2 presents the various chronic diseases among the three groups based on sleep duration. Among the enrolled schizophrenia patients, the most common comorbid chronic diseases were hypertension (8.0%), diabetes (6.8%) and hyperlipidemia (3.2%). Univariate analysis revealed that hypertension, arthritis and intervertebral disc disease were significantly different among the three groups. The age of onset and illness duration were not normally distributed.
Table 2.
Comparison of chronic diseases among three groups by sleep duration
| Variables | Total (n = 6024) | Short Sleepers (n = 521) | Medium Sleepers (n = 2653) | Long Sleepers (n = 2850) | Statistics | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | X 2 | P | |
| Hypertension | 484 | 8.0 | 60 | 11.5 | 228 | 8.6 | 196 | 6.9 | 14.83 | 0.001 |
| Diabetes | 410 | 6.8 | 41 | 7.9 | 189 | 7.1 | 180 | 6.3 | 2.43 | 0.29 |
| Coronary disease | 63 | 1.0 | 10 | 1.9 | 29 | 1.1 | 24 | 0.8 | 5.04 | 0.08 |
| COPD | 19 | 0.3 | 4 | 0.8 | 5 | 0.2 | 10 | 0.4 | 4.86 | 0.08 |
| Malignant tumore | 11 | 0.2 | 3 | 0.6 | 5 | 0.2 | 3 | 0.1 | 5.36 | 0.06 |
| Stroke | 27 | 0.4 | 1 | 0.2 | 15 | 0.6 | 11 | 0.4 | 1.83 | 0.40 |
| Chronic hepatitis | 65 | 1.1 | 8 | 1.5 | 27 | 1.0 | 30 | 1.1 | 1.12 | 0.56 |
| Anemia | 96 | 1.6 | 12 | 2.3 | 40 | 1.5 | 44 | 1.5 | 1.84 | 0.39 |
| Hyperlipidemia | 192 | 3.2 | 24 | 4.6 | 80 | 3.0 | 88 | 3.1 | 3.74 | 0.15 |
| Conscientious disorder/Dementia | 54 | 0.9 | 4 | 0.8 | 21 | 0.8 | 29 | 1.0 | 0.89 | 0.63 |
| Parkinson’s disease | 8 | 0.1 | 1 | 0.2 | 3 | 0.1 | 4 | 0.1 | 0.22 | 0.89 |
| Epilepsy | 23 | 0.4 | 5 | 1.0 | 9 | 0.3 | 9 | 0.3 | 5.02 | 0.08 |
| Chronic gastroenteritis | 74 | 1.2 | 10 | 1.9 | 37 | 1.4 | 27 | 0.9 | 4.51 | 0.10 |
| Arthritis | 57 | 0.9 | 11 | 2.1 | 27 | 1.0 | 19 | 0.7 | 10.06 | 0.007 |
| Intervertebral disc disease | 53 | 0.9 | 12 | 2.3 | 23 | 0.9 | 18 | 0.6 | 14.12 | 0.001 |
| Urinary tract stones | 29 | 0.5 | 5 | 1.0 | 14 | 0.5 | 10 | 0.4 | 3.62 | 0.16 |
COPD, chronic obstructive pulmonary disease
Multinomial logistic regression analyses of the entire cohort
Table 3 illustrates the association between short sleepers, long sleepers and sociodemographic, clinical variables. It was observed that current smoker (OR = 1.37, 95% CI: 1.03–1.82), outpatients (OR = 1.84, 95% CI: 1.42–2.38), BZD (OR = 1.30, 95% CI: 1.02–1.64), side effects (OR = 1.64, 95% CI: 1.30–2.06), comorbidities (OR = 1.33, 95% CI: 1.04–1.69), age of onset (OR = 1.01, 95% CI: 1.000-1.03), and illness duration (OR = 1.002, 95% CI: 1.000-1.003) were positively associated with short sleep duration, whereas personal annual income ≥ 40 000 yuan (OR = 0.59, 95% CI: 0.39–0.91) was negatively associated with short sleep duration.
Table 3.
Adjusted odds ratios (OR) and 95% confidence intervals of socio-demographic and clinical factors in relation to sleep duration
| Variables | Short vs. medium | Long vs. medium | ||||
|---|---|---|---|---|---|---|
| OR | 95%CI | P | OR | 95%CI | P | |
| Age | ||||||
| 18–34 | 1.00 | 1.00 | ||||
| 35–44 | 0.69 | 0.46–1.04 | 0.08 | 0.78 | 0.64–0.96 | 0.02 |
| 45–54 | 0.91 | 0.56–1.48 | 0.71 | 0.72 | 0.54–0.95 | 0.02 |
| 55–64 | 1.04 | 0.56–1.94 | 0.89 | 0.63 | 0.43–0.93 | 0.02 |
| ≥ 65 | 0.63 | 0.27–1.44 | 0.27 | 0.53 | 0.31–0.88 | 0.01 |
| Female | 1.22 | 0.95–1.56 | 0.11 | 0.92 | 0.80–1.06 | 0.30 |
| Education ≤ 9 years | 0.87 | 0.66–1.14 | 0.32 | 1.10 | 0.94–1.28 | 0.22 |
| Marital status | ||||||
| Single/Divorced/Separated | 0.92 | 0.72–1.19 | 0.55 | 1.03 | 0.89–1.20 | 0.62 |
| Personal annul income, yuan | ||||||
| < 10,000 | 1.12 | 0.89–1.41 | 0.32 | 1.23 | 1.08–1.41 | 0.002 |
| 10,000–39,999 | 1.00 | 1.00 | ||||
| ≥ 40,000 | 0.59 | 0.39–0.91 | 0.01 | 1.23 | 1.006–1.52 | 0.04 |
| Current smoker | 1.37 | 1.03–1.82 | 0.02 | 0.94 | 0.79–1.11 | 0.47 |
| Exercise | ||||||
| Never | 1.17 | 0.82–1.66 | 0.37 | 0.89 | 0.72–1.10 | 0.29 |
| 1–3 times/month | 0.72 | 0.44–1.17 | 0.19 | 0.64 | 0.49–0.83 | 0.001 |
| 1–5 times/week | 0.68 | 0.44–1.04 | 0.08 | 0.55 | 0.43–0.71 | < 0.001 |
| Everyday | 1.00 | 1.00 | ||||
| Outpatients | 1.84 | 1.42–2.38 | < 0.001 | 0.74 | 0.65–0.85 | < 0.001 |
| Chronic patients | 0.91 | 0.39–2.08 | 0.82 | 1.80 | 1.09–2.97 | 0.02 |
| FGAs | 0.97 | 0.76–1.25 | 0.86 | 1.49 | 1.30–1.71 | < 0.001 |
| SGAs | 0.86 | 0.63–1.17 | 0.35 | 1.11 | 0.91–1.36 | 0.28 |
| BZDs | 1.30 | 1.02–1.64 | 0.03 | 0.99 | 0.86–1.14 | 0.96 |
| Side effects | 1.64 | 1.30–2.06 | < 0.001 | 1.40 | 1.23–1.60 | < 0.001 |
| Comorbidities | 1.33 | 1.04–1.69 | 0.02 | 0.91 | 0.78–1.05 | 0.22 |
| Age of onset, years | 1.01 | 1.000-1.03 | 0.04 | 0.99 | 0.98–1.006 | 0.33 |
| Illness duration, months | 1.002 | 1.000-1.003 | 0.01 | 1.000 | 0.99–1.001 | 0.49 |
BZD, benzodiazepine; FGA, first-generation antipsychotic; SGA, second-generation antipsychotic
Further analyses showed that personal annul income < 10 000 yuan (OR = 1.23, 95% CI: 1.08–1.41), personal annual income ≥ 40 000 yuan (OR = 1.23, 95% CI: 1.006–1.52), chronic patients (OR = 1.80, 95% CI: 1.09–2.97), having FGAs (OR = 1.49, 95% CI: 1.30–1.71) and side effects (OR = 1.40, 95% CI: 1.23–1.60) were positively associated with long sleep duration. Aged 35 to 44 (OR = 0.78, 95% CI: 0.64–0.96), aged 45 to 54 (OR = 0.72, 95% CI: 0.54–0.95), aged 55 to 64 (OR = 0.63, 95% CI: 0.43–0.93), aged ≥ 65 (OR = 0.53, 95% CI: 0.31–0.88), exercise 1–3 times/month (OR = 0.64, 95% CI: 0.49–0.83), exercise 1–5 times/week (OR = 0.55, 95% CI: 0.43–0.71), outpatients (OR = 0.74, 95% CI: 0.65–0.85) were negatively associated with long sleep duration.
Table 4 presents the adjusted OR of specific chronic diseases classified based on short and long sleeps. Compared to medium sleepers, short sleepers and long sleepers had no significant predisposition.
Table 4.
Adjusted odds ratios (OR) and 95% confidence intervals of specific chronic diseases in relation to short and long sleeps
| Variables | Short vs. medium | Long vs. medium | ||||
|---|---|---|---|---|---|---|
| OR | 95%CI | P | OR | 95%CI | P | |
| Hypertension | 1.06 | 0.75–1.51 | 0.71 | 0.95 | 0.75–1.20 | 0.70 |
| Arthritis | 1.20 | 0.51–2.81 | 0.66 | 0.78 | 0.40–1.55 | 0.49 |
| Intervertebral disc disease | 1.49 | 0.63–3.51 | 0.35 | 1.05 | 0.54–2.04 | 0.86 |
Multinomial logistic regression models were used in the statistical analysis. Socio-demographics, lifestyle factors, source of patient, drug, side effects, age of onset, illness duration were adjusted for in the models
Stratified analysis
There was no significant collinearity between age, age of onset and illness duration (VIF < 10, tolerance > 0.1). Similarly, we found that there was no significant correlation between age range and comorbidities (C = 0.26), gender and smoking (C = 0.38), gender and drinking (C = 0.17), income and education (ρ = 0.16). Moreover, there were no interaction effects between smoking, drinking and gender. However, interaction effects were found between the source of patients and FGAs, SGAs, BZDs, and comorbidities.
Table 5 presents the characteristics of inpatients and outpatients based on sleep duration. Logistic regressions analyses were conducted separately for inpatients and outpatients to identify factors associated with long sleep duration, as this was the most frequently reported category. Subgroup analysis revealed that being female (OR = 0.81, 95% CI: 0.66–0.98) was a specific factor associated with long sleep duration among inpatients while being overweight (OR = 1.26, 95% CI: 1.03–1.54) was a specific factor for outpatients.
Table 5.
Socio-demographic and clinical characteristics by sleep duration among the inpatients and outpatients (n = 5960)
| Variables | Inpatients (n = 2684) | Outpatients (n = 3276) | ||||||
|---|---|---|---|---|---|---|---|---|
| n | short sleepers (n = 148) |
medium sleepers (n = 1068) | long sleepers (n = 1468) | n | short sleepers (n = 372) |
medium sleepers (n = 1567) | long sleepers (n = 1337) | |
| Age, years | 2684 | 3276 | ||||||
| 18–34 | 40 (27.0%) | 332 (31.1%) | 547 (37.3%) | 58 (15.6%) | 369 (23.5%) | 413 (30.9%) | ||
| 35–44 | 26 (17.6%) | 262 (24.5%) | 368 (25.1%) | 67 (18.0%) | 384 (24.5%) | 344 (25.7%) | ||
| 45–54 | 32 (21.6%) | 227 (21.3%) | 335 (22.8%) | 119 (32.0%) | 445 (28.4%) | 319 (23.9%) | ||
| 55–64 | 38 (25.7%) | 171 (16.0%) | 158 (10.8%) | 94 (25.3%) | 247 (15.8%) | 179 (13.4%) | ||
| ≥ 65 | 12 (8.1%) | 76 (7.1%) | 60 (4.1%) | 34 (9.1%) | 122 (7.8%) | 82 (6.1%) | ||
| Gender | 2684 | 3276 | ||||||
| Male | 86 (58.1%) | 690 (64.6%) | 1024 (69.8%) | 173 (46.5%) | 830 (53.0%) | 704 (52.7%) | ||
| Female | 62 (41.9%) | 378 (35.4%) | 444 (30.2%) | 199 (53.5%) | 737 (47.0%) | 633 (47.3%) | ||
| BMI, kg/m2 | 2659 | 3272 | ||||||
| < 18.5 | 23 (15.6%) | 125 (11.8%) | 209 (14.4%) | 30 (8.1%) | 103 (6.6%) | 80 (6.0%) | ||
| 18.5 ≤ BMI < 25 | 87 (59.2%) | 688 (64.7%) | 928 (64.0%) | 227 (61.0%) | 960 (61.3%) | 748 (56.0%) | ||
| 25 ≤ BMI < 30 | 28 (19.0%) | 223 (21.0%) | 259 (17.9%) | 95 (25.5%) | 393 (25.1%) | 392 (29.4%) | ||
| ≥ 30 | 9 (6.1%) | 27 (2.5%) | 53 (3.7%) | 20 (5.4%) | 109 (7.0%) | 115 (8.6%) | ||
| Education level | 2617 | 3246 | ||||||
| > 9 years | 57 (38.8%) | 245 (23.6%) | 252 (17.6%) | 78 (21.1%) | 424 (27.3%) | 338 (25.5%) | ||
| ≤ 9 years | 90 (61.2%) | 793 (76.4%) | 1180 (82.4%) | 292 (78.9%) | 1128 (72.7%) | 986 (74.5%) | ||
| Marital status | 2661 | 3267 | ||||||
| Married/Cohabitation | 48 (32.4%) | 279 (26.3%) | 355 (24.5%) | 226 (60.8%) | 803 (51.4%) | 593 (44.5%) | ||
| Single/Divorced/Separated | 100 (67.6%) | 783 (73.7%) | 1096 (75.5%) | 146 (39.2%) | 758 (48.6%) | 741 (55.5%) | ||
| Personal annul income, yuan | 2632 | 3249 | ||||||
| < 10,000 | 60 (41.4%) | 503 (47.9%) | 796 (55.4%) | 191 (52.0%) | 737 (47.3%) | 729 (55.0%) | ||
| 10,000–39,999 | 65 (44.8%) | 376 (35.8%) | 421 (29.3%) | 150 (40.9%) | 634 (40.7%) | 462 (34.9%) | ||
| ≥ 40,000 | 20 (13.8%) | 172 (16.4%) | 219 (15.3%) | 26 (7.1%) | 186 (11.9%) | 134 (10.1%) | ||
| Current smoker | 2682 | 3271 | ||||||
| No | 120 (81.1%) | 924 (86.5%) | 1285 (87.7%) | 280 (75.3%) | 1214 (77.5%) | 1020 (76.5%) | ||
| Yes | 28 (18.9%) | 144 (13.5%) | 181 (12.3%) | 92 (24.7%) | 352 (22.5%) | 313 (23.5%) | ||
| Current drinker | 2684 | 3276 | ||||||
| No | 145 (98.0%) | 1011 (94.7%) | 1417 (96.5%) | 346 (93.0%) | 1478 (94.3%) | 1259 (94.2%) | ||
| Yes | 3 (2.0%) | 57 (5.3%) | 51 (3.5%) | 26 (7.0%) | 89 (5.7%) | 78 (5.8%) | ||
| Exercise | 2668 | 3270 | ||||||
| Never | 101 (69.7%) | 630 (59.4%) | 996 (68.1%) | 224 (60.2%) | 810 (51.8%) | 769 (57.6%) | ||
| 1–3 times/month | 15 (10.3%) | 218 (20.6%) | 220 (15.0%) | 31 (8.3%) | 178 (11.4%) | 127 (9.5%) | ||
| 1–5 times/week | 14 (9.7%) | 158 (14.9%) | 145 (9.9%) | 61 (16.4%) | 346 (22.1%) | 225 (16.9%) | ||
| Everyday | 15 (10.3%) | 54 (5.1%) | 102 (7.0%) | 56 (15.1%) | 230 (14.7%) | 213 (16.0%) | ||
| State of disease | 2683 | 3267 | ||||||
| First episode | 17 (11.5%) | 33 (3.1%) | 34 (2.3%) | 2 (0.5%) | 25 (1.6%) | 14 (1.0%) | ||
| Chronic patients | 131 (88.5%) | 1035 (96.9%) | 1433 (97.7%) | 370 (99.5%) | 1535 (98.4%) | 1321 (99.0%) | ||
| FGAs | 2684 | 21 (14.2%) | 254 (23.8%) | 556 (37.9%) | 3276 | 131 (35.2%) | 461 (29.4%) | 468 (35.0%) |
| SGAs | 2684 | 143 (96.6%) | 1005 (94.1%) | 1325 (90.3%) | 3276 | 275 (73.9%) | 1272 (81.2%) | 1141 (85.3%) |
| BZDs | 2684 | 35 (23.6%) | 283 (26.5%) | 451 (30.7%) | 3276 | 108 (29.0%) | 335 (21.4%) | 283 (21.2%) |
| Side effects | 2404 | 58 (46.4%) | 365 (38.2%) | 586 (44.3%) | 2694 | 108 (35.3%) | 283 (22.9%) | 368 (32.0%) |
| Comorbidities | 2542 | 54 (41.2%) | 302 (29.8%) | 322 (23.0%) | 3125 | 108 (31.2%) | 313 (21.0%) | 291 (22.6%) |
| Mean (SD) | Mean (SD) | Mean (SD) | Mean (SD) | Mean (SD) | Mean (SD) | |||
| Age of onset, years | 2677 | 29.2 (11.3) | 26.6 (9.6) | 25.5 (9.6) | 3269 | 30.8 (12.4) | 29.2 (11.6) | 26.3 (11.1) |
| Illness duration, months | 2689 | 207.0 (159.9) | 198.9 (143.8) | 184.4 (130.0) | 3275 | 222.8 (142.2) | 191.9 (129.5) | 197.5 (129.6) |
BMI, Body Mass Index; BZD, benzodiazepine; FGA, first-generation antipsychotic; SGA, second-generation antipsychotic
Discussion
In this study, we investigated the prevalence of short and long sleep duration among patients with schizophrenia, and their associated factors. The results indicated that individuals with schizophrenia were more susceptible to long sleep duration, recorded in 47.2% of the participants, whereas 8.6% experienced short sleep duration. The mean sleep duration of these patients was 9.3 h. Previous research has demonstrated that the mean total sleep time of schizophrenia patients was 8.2 h and the frequency of long sleepers was 43.5%, which were lower than our findings [23]. The sample size of this study is larger, and the sampling method makes the participants more representative. There are significant genetic associations between schizophrenia and co-morbid sleep disorders, implicating the circadian system, as well as dopamine and histamine metabolism and signal transduction pathways [24]. Sleep disturbances in schizophrenia may partly result from altered expression of circadian clock genes, which contribute to abnormal sleep rhythms [25]. Furthermore, sleep disturbances might increase dopamine release and sensitivity, increasing the risk of psychosis. Impaired melatonin regulation has been reported to induce sleep irregularities [26].
In this study, male patients exhibited a higher proportion of long sleep (61.8%), whereas female patients had a higher proportion of short sleep duration (50.1%). Among hospitalized patients, female was less likely to experience long sleep duration. This may be due to the possibility that male patients likely receive higher doses of medication, which could contribute to longer sleep durations [27]. Women were reported having an early timing of circadian rhythms, particularly for endogenous temperature and melatonin, partly as a consequence of a significantly shorter circadian period. A possible explanation is that sleep is influenced by sex steroids, and sleep in women is more sensitive to changes in the ovarian steroidal milieu [28]. In addition, the sleep-inflammation link has been reported to be stronger in women [29].
In the multinomial logistic regression analyses, we found that higher income was negatively associated with short sleep, whereas low income and high income were positively associated with long sleep duration. Individuals with higher incomes generally tend to have greater access to education and healthcare services, which may enhance their knowledge about sleep health. Moreover, it has been shown that lower socioeconomic status correlates with shorter self-reported sleep duration [30]. In our analysis, we observed that the long sleep duration was negatively associated with aging. It has been demonstrated that sleep patterns change with aging, including shortened nocturnal sleep duration, increased number of nocturnal awakenings and time spent awake during the night. With normal aging, the circadian system and sleep homeostasis weaken, and the secretion of sleep-related hormones also changes in amount and pattern [31]. In our study, current smokers appeared to be more likely to have short sleep duration. Current smoking exhibited a positive correlation with difficulty falling asleep, late bedtime, waking up earlier than expected, and long nap time [32]. Nicotine influences the duration and quality of sleep by stimulating neurotransmitters that modulate the circadian cycle [33]. A previous report indicated that genetic variants linked to poorer sleep quality may also increase the risk of smoking [34].
Patients with schizophrenia tend to be sedentary and exhibit lower levels of physical activity compared to the general population [35]. In this study, 59.8% of participants reported never exercising. The results revealed that regular exercise was negatively associated with long sleep duration, suggesting that it can exert a protective effect on sleep quality. Accumulating evidence has demonstrated that exercise may be a nonpharmacologic treatment for sleep disturbances [36]. Moreover, exercise can improve positive and negative symptoms, depressive and anxiety symptoms, as well as the global functioning and quality of life for schizophrenia patients. Exercise has been reported to increase the hippocampal volume, thereby improving memory and overall symptoms [37]. It also increases the serum levels of brain-derived neurotrophic factor (BDNF), enhancing the neurocognitive functions [38]. Additionally, engaging in physical activity can mitigate the health risks associated with antipsychotic medications, such as metabolic syndrome, and decrease mortality rates [37]. Furthermore, exercise fosters a sense of social participation, promotes enjoyment, builds confidence, and instills a sense of achievement, all of which can promote the confidence of patients in their rehabilitation journey [39].
In this study, outpatients tended to have short sleep and less likely to have long sleep duration. This may be explained by the fact that inpatients generally received higher doses of medication, such as antipsychotic polypharmacy, which is linked to inpatient status [40]. Antipsychotics are the primary treatments for schizophrenia, but they have been linked to the occurrence of several side effects. SGAs have been recognized to induce sleep-promoting effects [41]. A meta-analysis of 32 oral antipsychotics in patients with multi-episode schizophrenia found that most of these antipsychotics exhibit sedative properties [42], which may increase sleep durations. To address the circadian misalignment and hormonal disruptions associated with metabolic regulation, nocturnal administration of melatonin has been suggested for patients treated with SGAs [43].
In China, community health institutions serve as the initial units involved in the administration and maintenance of treatment for schizophrenia patients. According to a national survey in 2020, the medication adherence rate among community-dwelling schizophrenia patients was 88.74%, with 70.00% taking medication regularly [44]. Schizophrenia in community-dwelling patients who report sleep disturbances tend to exhibit poorer adherence to treatment [19]. In our study, factors specific to outpatients that were positively associated with long sleep duration included being overweight, which may be partly due to obstructive sleep apnea (OSA). Increased weight and BMI were found to be significantly associated with diagnosis of OSA in community-dwelling people with schizophrenia [45]. Moreover, OSA is more prevalent in schizophrenia patients than in the general population [46], with obesity being a significant contributing factor to this increased prevalence [47].
In this study, several chronic diseases were found to be comorbidities of schizophrenia. The most common conditions were hypertension (8.0%), diabetes (6.8%), and hyperlipidemia (3.2%), consistent with previous findings in Taiwan [48] and Sweden [49]. Furthermore, hypertension was significantly associated with longer hospital stays and increased hospitalization frequency among inpatients [50]. Individuals with schizophrenia often exhibit significant somatic comorbidities, which can decrease life expectancy [51]. Poor physical health in this population can lead to reduced physical activity and a loss of motivation, thereby increasing the risk of sleep disturbances. The relationship between sleep duration and the risk of metabolic syndrome presented a U-shaped curve. Short and long sleep increased the risk of obesity by 14% and 15%, respectively [52]. Furthermore, long sleep duration can damage the whole-body energy metabolism, promoting the occurrence of obesity and type 2 diabetes mellitus (T2DM) via several compounding mechanisms, including poor sleep quality, a sedentary lifestyle, unhealthy dietary choices, and desynchrony between circadian and behavioral states [53].
This study underscores the prevalence of abnormal sleep duration in individuals with schizophrenia and emphasize the urgent need for targeted interventions to address sleep disturbances in this population. However, it is important to acknowledge certain limitations of this study. Firstly, sleep duration was assessed using self-reported measures, which may be subject to recall bias and may not accurately reflect actual sleep patterns compared to objective measures such as polysomnography. Secondly, the questionnaire was mainly designed to solely collect data on sleep duration over the past month. Thus, future studies should investigate chronic sleep disturbances to obtain a more comprehensive understanding. Thirdly, the study was performed at a single province in China, limiting the generalizability of the results to other regions. Fourthly, we did not account for the type or dosage of medication in the analysis, which could influence sleep duration. Finally, given that this is a cross-sectional study, we could not establish causality between sleep duration and associated factors.
Conclusion
Overall, we found that the abnormal sleep duration and somatic comorbidities are highly frequent in patients with schizophrenia. Our findings highlight the complex relationships between socioeconomic information, clinical factors, and sleep duration in schizophrenia, emphasizing the need for targeted interventions and management strategies for sleep duration in this population.
Acknowledgements
This study is supported by Guangdong Provincial Innovation Platform of Translational Medicine (Early recognition and intervention of major mental diseases), Guangdong Provincial Innovation Platform of Public Health. The authors thank all the clinicians and the participants for their contribution to the study.
Abbreviations
- DALYs
Disability-adjusted life years
- BMI
Body Mass Index
- FGA
First-generation antipsychotic
- SGA
Second-generation antipsychotic
- BZD
Benzodiazepine
- ICD-10
10th Revision of the International Classification of diseases
- SD
Standard deviation
- OR
Odds ratio
- CI
Confidence interval
- OSA
Obstructive sleep apnea
- T2DM
Type2 diabetes mellitus
- BDNF
Brain Derived Neurotrophic Factor
Author contributions
All authors contributed to the study conception and design. Material preparation, data collection was performed by WYT, HCL, SBW. MD and DDL analyzed and interpreted the patient data. The first draft of the manuscript was written by MD and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
Funding
This study was supported by the Medical Scientific Research Foundation of Guangdong Province of China (grant number: C2018026).
Data availability
All data generated and/or analyzed during this study are included in this published article.
Declarations
Ethics approval and consent to participate
Informed consent to participate was obtained from the patients or their legal guardians. The Ethics Committee of Guangdong Provincial People’s Hospital approved the study protocol.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Min Dong and Dan-Dan Liao contributed equally to this work.
References
- 1.Huang Y, Wang Y, Wang H, Liu Z, Yu X, Yan J, Yu Y, Kou C, Xu X, Lu J, et al. Prevalence of mental disorders in China: a cross-sectional epidemiological study. Lancet Psychiatry. 2019;6(3):211–24. [DOI] [PubMed] [Google Scholar]
- 2.Solmi M, Seitidis G, Mavridis D, Correll CU, Dragioti E, Guimond S, Tuominen L, Dargél A, Carvalho AF, Fornaro M, et al. Incidence, prevalence, and global burden of schizophrenia - data, with critical appraisal, from the global burden of Disease (GBD) 2019. Mol Psychiatry. 2023;28(12):5319–27. [DOI] [PubMed] [Google Scholar]
- 3.Maramis MM, Sofyan Almahdy M, Atika A, Bagus Jaya Lesmana C, Gerick Pantouw J. The biopsychosocial-spiritual factors influencing relapse of patients with schizophrenia. Int J Soc Psychiatry. 2022;68(8):1824–33. [DOI] [PubMed] [Google Scholar]
- 4.Oakley P, Kisely S, Baxter A, Harris M, Desoe J, Dziouba A, Siskind D. Increased mortality among people with schizophrenia and other non-affective psychotic disorders in the community: a systematic review and meta-analysis. J Psychiatr Res. 2018;102:245–53. [DOI] [PubMed] [Google Scholar]
- 5.Rattenborg NC, de la Iglesia HO, Kempenaers B, Lesku JA, Meerlo P, Scriba MF. Sleep research goes wild: new methods and approaches to investigate the ecology, evolution and functions of sleep. Philos Trans R Soc Lond B Biol Sci 2017, 372(1734). [DOI] [PMC free article] [PubMed]
- 6.Hirshkowitz M, Whiton K, Albert SM, Alessi C, Bruni O, DonCarlos L, Hazen N, Herman J, Katz ES, Kheirandish-Gozal L, et al. National Sleep Foundation’s sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40–3. [DOI] [PubMed] [Google Scholar]
- 7.Antza C, Kostopoulos G, Mostafa S, Nirantharakumar K, Tahrani A. The links between sleep duration, obesity and type 2 diabetes mellitus. J Endocrinol. 2021;252(2):125–41. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Brady EM, Bodicoat DH, Hall AP, Khunti K, Yates T, Edwardson C, Davies MJ. Sleep duration, obesity and insulin resistance in a multi-ethnic UK population at high risk of diabetes. Diabetes Res Clin Pract. 2018;139:195–202. [DOI] [PubMed] [Google Scholar]
- 9.Yin J, Jin X, Shan Z, Li S, Huang H, Li P, Peng X, Peng Z, Yu K, Bao W, et al. Relationship of Sleep Duration with all-cause Mortality and Cardiovascular events: a systematic review and dose-response Meta-analysis of prospective cohort studies. J Am Heart Assoc. 2017;6(9):e005947. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Batalla-Martín D, Belzunegui-Eraso A, Miralles Garijo E, Martínez Martín E, Romaní Garcia R, Heras JSM, Lopez-Ruiz M, Martorell-Poveda MA. Insomnia in Schizophrenia patients: Prevalence and Quality of Life. Int J Environ Res Public Health 2020, 17(4). [DOI] [PMC free article] [PubMed]
- 11.Boiko DI, Chopra H, Bilal M, Kydon PV, Herasymenko LO, Rud VO, Bodnar LA, Vasylyeva GY, Isakov RI, Zhyvotovska LV, et al. Schizophrenia and disruption of circadian rhythms: an overview of genetic, metabolic and clinical signs. Schizophr Res. 2024;264:58–70. [DOI] [PubMed] [Google Scholar]
- 12.Chan MS, Chung KF, Yung KP, Yeung WF. Sleep in schizophrenia: a systematic review and meta-analysis of polysomnographic findings in case-control studies. Sleep Med Rev. 2017;32:69–84. [DOI] [PubMed] [Google Scholar]
- 13.Kaskie RE, Graziano B, Ferrarelli F. Schizophrenia and sleep disorders: links, risks, and management challenges. Nat Sci Sleep. 2017;9:227–39. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Petrovsky N, Ettinger U, Hill A, Frenzel L, Meyhöfer I, Wagner M, Backhaus J, Kumari V. Sleep deprivation disrupts prepulse inhibition and induces psychosis-like symptoms in healthy humans. J Neuroscience: Official J Soc Neurosci. 2014;34(27):9134–40. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Mulligan LD, Haddock G, Emsley R, Neil ST, Kyle SD. High resolution examination of the role of sleep disturbance in predicting functioning and psychotic symptoms in schizophrenia: a novel experience sampling study. J Abnorm Psychol. 2016;125(6):788–97. [DOI] [PubMed] [Google Scholar]
- 16.Laskemoen JF, Büchmann C, Barrett EA, Collier-Høegh M, Haatveit B, Vedal TJ, Ueland T, Melle I, Aas M, Simonsen C. Do sleep disturbances contribute to cognitive impairments in schizophrenia spectrum and bipolar disorders? Eur Arch Psychiatry Clin NeuroSci. 2020;270(6):749–59. [DOI] [PubMed] [Google Scholar]
- 17.Wang WL, Zhou YQ, Chai NN, Li GH. Sleep disturbance and quality of life in clinically stable inpatients with schizophrenia in rural China. Qual life Research: Int J Qual life Aspects Treat care Rehabilitation. 2020;29(10):2759–68. [DOI] [PubMed] [Google Scholar]
- 18.Li SX, Lam SP, Zhang J, Yu MW, Chan JW, Chan CS, Espie CA, Freeman D, Mason O, Wing YK. Sleep disturbances and suicide risk in an 8-Year longitudinal study of Schizophrenia-Spectrum disorders. Sleep. 2016;39(6):1275–82. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Afonso P, Brissos S, Cañas F, Bobes J, Bernardo-Fernandez I. Treatment adherence and quality of sleep in schizophrenia outpatients. Int J Psychiatry Clin Pract. 2014;18(1):70–6. [DOI] [PubMed] [Google Scholar]
- 20.Ferrarelli F. Sleep spindles as neurophysiological biomarkers of schizophrenia. Eur J Neurosci. 2024;59(8):1907–17. [DOI] [PubMed] [Google Scholar]
- 21.Wang Z, Chen M, Wei YZ, Zhuo CG, Xu HF, Li WD, Ma L. The causal relationship between sleep traits and the risk of schizophrenia: a two-sample bidirectional mendelian randomization study. BMC Psychiatry. 2022;22(1):399. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Wang F, Yang Y, Tan WY, Lin HC, Yang CJ, Lin YQ, Jia FJ, Wang SB, Hou CL. Patterns and correlates of insight among patients with schizophrenia in China: a network perspective. Asian J Psychiatry. 2023;88:103735. [DOI] [PubMed] [Google Scholar]
- 23.Hou CL, Zang Y, Ma XR, Cai MY, Li Y, Jia FJ, Lin YQ, Chiu HFK, Ungvari GS, Ng CH, et al. The relationship between sleep patterns, Quality of Life, and Social and clinical characteristics in Chinese patients with Schizophrenia. Perspect Psychiatr Care. 2017;53(4):342–9. [DOI] [PubMed] [Google Scholar]
- 24.Assimakopoulos K, Karaivazoglou K, Skokou M, Kalogeropoulou M, Kolios P, Gourzis P, Patrinos GP, Tsermpini EE. Genetic Variations Associated with Sleep disorders in patients with Schizophrenia: a systematic review. Med (Basel Switzerland) 2018, 5(2). [DOI] [PMC free article] [PubMed]
- 25.Johansson AS, Owe-Larsson B, Hetta J, Lundkvist GB. Altered circadian clock gene expression in patients with schizophrenia. Schizophr Res. 2016;174(1–3):17–23. [DOI] [PubMed] [Google Scholar]
- 26.Yates NJ. Schizophrenia: the role of sleep and circadian rhythms in regulating dopamine and psychosis. Rev Neurosci. 2016;27(7):669–87. [DOI] [PubMed] [Google Scholar]
- 27.Chen MH, Korenic SA, Wickwire EM, Wijtenburg SA, Hong LE, Rowland LM. Sex differences in subjective sleep quality patterns in Schizophrenia. Behav Sleep Med. 2020;18(5):668–79. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Mong JA, Cusmano DM. Sex differences in sleep: impact of biological sex and sex steroids. Philos Trans R Soc Lond B Biol Sci. 2016;371(1688):20150110. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Lee EE, Ancoli-Israel S, Eyler LT, Tu XM, Palmer BW, Irwin MR, Jeste DV. Sleep disturbances and inflammatory biomarkers in Schizophrenia: focus on sex differences. Am J Geriatric Psychiatry: Official J Am Association Geriatric Psychiatry. 2019;27(1):21–31. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Whinnery J, Jackson N, Rattanaumpawan P, Grandner MA. Short and long sleep duration associated with race/ethnicity, sociodemographics, and socioeconomic position. Sleep. 2014;37(3):601–11. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Li J, Vitiello MV, Gooneratne NS. Sleep in normal aging. Sleep Med Clin. 2018;13(1):1–11. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Xie Y, Sun P, Huang H, Wu J, Ba Y, Zhou G, Yu F, Zhang D, Zhang Y, Qie R, et al. Network analysis of smoking-related sleep characteristics in Chinese adults. Ann Med. 2024;56(1):2332424. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 33.Zhang L, Samet J, Caffo B, Punjabi NM. Cigarette smoking and nocturnal sleep architecture. Am J Epidemiol. 2006;164(6):529–37. [DOI] [PubMed] [Google Scholar]
- 34.Gibson M, Munafò MR, Taylor AE, Treur JL. Evidence for genetic correlations and bidirectional, causal effects between Smoking and Sleep behaviors. Nicotine Tob Res. 2019;21(6):731–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 35.Zarbo C, Rota M, Calza S, Crouter SE, Ekelund U, Barlati S, Bussi R, Clerici M, Placenti R, Paulillo G et al. Ecological monitoring of physical activity, emotions and daily life activities in schizophrenia: the DiAPAson study. BMJ Ment Health 2023, 26(1). [DOI] [PMC free article] [PubMed]
- 36.Kelley GA, Kelley KS. Exercise and sleep: a systematic review of previous meta-analyses. J Evid Based Med. 2017;10(1):26–36. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Girdler SJ, Confino JE, Woesner ME. Exercise as a treatment for Schizophrenia: a review. Psychopharmacol Bull. 2019;49(1):56–69. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 38.Kim HJ, Song BK, So B, Lee O, Song W, Kim Y. Increase of circulating BDNF levels and its relation to improvement of physical fitness following 12 weeks of combined exercise in chronic patients with schizophrenia: a pilot study. Psychiatry Res. 2014;220(3):792–6. [DOI] [PubMed] [Google Scholar]
- 39.Chen C, Yang Y, Ye X, Jin Y, Cai Z, Zheng J. Impact of aerobic exercise on cognitive function in patients with schizophrenia during daily nursing: a protocol for systematic review and meta-analysis. Medicine. 2021;100(1):e23876. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 40.Lung SLM, Lee HME, Chen YHE, Chan KWS, Chang WC, Hui LMC. Prevalence and correlates of antipsychotic polypharmacy in Hong Kong. Asian J Psychiatry. 2018;33:113–20. [DOI] [PubMed] [Google Scholar]
- 41.Cohrs S. Sleep disturbances in patients with schizophrenia: impact and effect of antipsychotics. CNS Drugs. 2008;22(11):939–62. [DOI] [PubMed] [Google Scholar]
- 42.Huhn M, Nikolakopoulou A, Schneider-Thoma J, Krause M, Samara M, Peter N, Arndt T, Bäckers L, Rothe P, Cipriani A, et al. Comparative efficacy and tolerability of 32 oral antipsychotics for the acute treatment of adults with multi-episode schizophrenia: a systematic review and network meta-analysis. Lancet. 2019;394(10202):939–51. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 43.Porfirio MC, Gomes de Almeida JP, Stornelli M, Giovinazzo S, Purper-Ouakil D, Masi G. Can melatonin prevent or improve metabolic side effects during antipsychotic treatments? Neuropsychiatr Dis Treat. 2017;13:2167–74. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 44.Zhang WF, Ma N, Wang X. Management and services for psychosis in the People’s Republic of China in 2020. Chin J Psychiatry. 2022;55(2):122–8. [Google Scholar]
- 45.Myles H, Myles N, Vincent AD, Wittert G, Adams R, Chandratilleke M, Liu D, Mercer J, Vakulin A, Chai-Coetzer CL, et al. Pilot cohort study of obstructive sleep apnoea in community-dwelling people with schizophrenia. Ir J Psychol Med. 2021;38(1):23–9. [DOI] [PubMed] [Google Scholar]
- 46.Wu YY, Chang ET, Yang YC, Chen SF, Hsu CY, Shen YC. Risk of obstructive sleep apnea in patients with schizophrenia: a nationwide population-based cohort study. Soc Psychiatry Psychiatr Epidemiol. 2020;55(12):1671–7. [DOI] [PubMed] [Google Scholar]
- 47.Myles H, Vincent A, Myles N, Adams R, Chandratilleke M, Liu D, Mercer J, Vakulin A, Wittert G, Galletly C. Obstructive sleep apnoea is more prevalent in men with schizophrenia compared to general population controls: results of a matched cohort study. Australasian Psychiatry: Bull Royal Australian New Z Coll Psychiatrists. 2018;26(6):600–3. [DOI] [PubMed] [Google Scholar]
- 48.Liao CH, Chang CS, Wei WC, Chang SN, Liao CC, Lane HY, Sung FC. Schizophrenia patients at higher risk of diabetes, hypertension and hyperlipidemia: a population-based study. Schizophr Res. 2011;126(1–3):110–6. [DOI] [PubMed] [Google Scholar]
- 49.Brostedt EM, Msghina M, Persson M, Wettermark B. Health care use, drug treatment and comorbidity in patients with schizophrenia or non-affective psychosis in Sweden: a cross-sectional study. BMC Psychiatry. 2017;17(1):416. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 50.Lamadé EK, Özer N, Schaupp B, Krumm B, Deuschle M, Häfner S. Association of hypertension, type 2 diabetes mellitus and dyslipidemia with the duration of inpatient treatments and recurrence of schizophrenia. J Psychosom Res. 2023;172:111436. [DOI] [PubMed] [Google Scholar]
- 51.Dieset I, Andreassen OA, Haukvik UK. Somatic comorbidity in Schizophrenia: some possible Biological mechanisms across the Life Span. Schizophr Bull. 2016;42(6):1316–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 52.Che T, Yan C, Tian D, Zhang X, Liu X, Wu Z. The Association between Sleep and metabolic syndrome: a systematic review and Meta-analysis. Front Endocrinol (Lausanne). 2021;12:773646. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 53.Tan X, Chapman CD, Cedernaes J, Benedict C. Association between long sleep duration and increased risk of obesity and type 2 diabetes: a review of possible mechanisms. Sleep Med Rev. 2018;40:127–34. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
All data generated and/or analyzed during this study are included in this published article.