A Systematic Review of Sleep Hygiene Strategy in CKD

Abstract

Introduction

Sleep hygiene strategies are often encouraged in people with chronic kidney disease (CKD). We aimed to summarize the existing evidence on sleep hygiene strategies in this population.

Methods

We searched 4 electronic databases (MEDLINE, EMBASE, CINAHL, and PsycINFO) up to July 2024. Studies of any design were eligible if they reported sleep hygiene strategies and sleep outcomes for adults with CKD. We extracted data using standardized tools and synthesized the results into each component of the sleep hygiene strategy. The effectiveness of each sleep hygiene strategy was summarized using meta-analysis and in a narrative manner.

Results

Thirty-eight articles were included. Most studies (45%) focused on bedtime activity, with exercise (standardized mean difference [SMD]: −1.05, 95% confidence interval [CI]: −2.03 to −0.07) and relaxation techniques (SMD: −1.54, 95% CI: −2.34 to −0.73) showing promising effects on sleep quality. However, the timing of these strategies varied, limiting the ability to generalize these strategies in relation to bedtime activity. Few studies (18%) demonstrated positive effects of sleep hygiene education (SMD: −0.82, 95% CI: −1.57 to −0.63), particularly when delivered as part of cognitive behavior therapy (CBT). Mixed results were found regarding the impact of alcohol, caffeine, and cigarettes on sleep disturbances and sleep disorders. Limited studies have been conducted on bedroom environment, sleep patterns, and daytime napping in patients with CKD.

Conclusion

This review showed that sleep hygiene education can be a useful strategy for improving sleep in people with CKD. Exercise and relaxation techniques may reduce sleep disturbances; however, further research is necessary to determine the optimal timing for these activities.

Graphical Abstract

Sleep is essential for the body to restore physical function, maintain mental health, and overall well-being¹; however, achieving adequate and restful sleep can be difficult for individuals with CKD. The prevalence of poor sleep quality and insomnia in patients with CKD is > 55%, and the number becomes even higher among those receiving dialysis (58%).² Insomnia describes the difficulty in falling asleep, staying asleep and feeling refreshed in the morning, capable of being diagnosed using preexisting criteria³ or revealed using self-reported questionnaires (e.g., Pittsburgh Sleep Quality Index [PSQI]).⁴ PSQI scores provide an indication of sleep quality and have been widely used to detect sleep problems in the CKD population. Although sleep quality can change with aging, patients under maintenance dialysis have worse sleep quality than age- and gender-matched individuals without CKD.⁵

Observational studies disclose that self-reported poor sleep quality and short sleep duration are significantly associated with an increased risk of incident CKD^6,7 and declining kidney function.⁸ In addition, sleep duration is an important risk factor for hypertension and diabetes,^9,10 both of which are major risk factors for CKD. A longitudinal study with 4.5 years of follow-up (n = 6785) using a wearable sleep-tracking device found that short (< 5 h/d) and long (> 10 h/d) sleep duration had 29% and 64% increased risk of hypertension, respectively.¹¹ Based on these data, the National Kidney Foundation¹² recommends that maintaining adequate sleep, particularly through establishing a healthy sleep habit, constitutes an important self-care strategy for individuals with CKD.

The first-line management for insomnia and poor sleep quality is CBT for insomnia.¹³ The core components of CBT for insomnia are stimulus control, sleep restriction, cognitive therapy, relaxation techniques, and sleep hygiene.¹⁴ Sleep hygiene (also known as healthy sleep habits) is fundamental to maintaining and improving sleep. These sleep hygiene strategies are often delivered via education alone or in combination with hypnotic medication, such as benzodiazepine, for people to improve sleep.¹⁵ Unlike pharmacological treatments or other non–sleep hygiene behavioral therapies that target specific symptoms or behaviors, sleep hygiene focuses on lifestyle and environmental changes that support natural sleep habits.¹⁶ It is safe, easy to implement, and empowers patients to take control of their care.¹⁶

CKD uniquely affects patients’ circadian rhythms¹⁷ and sleep patterns, making sleep hygiene practices particularly important for this cohort. In addition, for those patients with CKD undergoing in-center hemodialysis (HD), the need for regular dialysis sessions, which can occur at various times, further misaligns sleep schedules, impacts sleep hygiene, and leads to poor sleep quality. Given the high prevalence and the potential impact that CKD has on sleep hygiene practices, sleep hygiene is often encouraged as part of patient self-care strategies.¹² However, the extent to which sleep hygiene principles and strategies are applicable to the CKD population is not clearly described. To address this gap, we conducted a systematic review to summarize the existing literature on sleep hygiene strategies in individuals with CKD. We sought to identify empirical evidence on the impact of common sleep hygiene strategies, such as regular sleep patterns, exercise, a comfortable sleep environment, and the avoidance of alcohol and caffeine, on sleep in people with different stages of CKD. By summarizing the current evidence, we hoped to identify key gaps that need to be addressed with further studies and to provide evidence-based sleep hygiene education for individuals with CKD who are experiencing sleep disturbances.

Methods

We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist (PRISMA)¹⁸ to report this review, and the protocol, although established, was not published in advance of this review.

Eligibility Criteria

We included studies that assessed sleep hygiene strategies in individuals with CKD. The review process first involved screening the titles and abstracts and reviewing full-text articles to assess eligibility. Two authors (GC and FY) completed this process independently using Covidence software.¹⁹ Disagreements were discussed and resolved through discussion. Eligible articles had to meet the following criteria: (i) population: adults (aged ≥ 18 years) with CKD (any stage), (ii) intervention: sleep hygiene strategies, (iii) comparator: not applicable, (iv) outcomes: any subjective or objective sleep outcome, and (v) any type of original research article published in a peer-reviewed journal (no editorial or commentaries). The following articles were excluded: (i) conference abstracts, reviews, and protocols; (ii) full-text articles not retrievable; and (iii) interventions unrelated to sleep hygiene strategy (e.g., dialysis adequacy or intensity).

Search Strategies

We developed the search terms in conjunction with an experienced librarian, and conducted the search in MEDLINE (Ovid), EMBASE (Ovid), CINAHL, and PsycINFO to identify relevant studies. Keywords included “sleep hygiene/habits” AND “chronic kidney disease” AND the search terms that aligned with sleep hygiene strategies recommended by the Sleep Health Foundation²⁰ and the Centre for Clinical Intervention.²¹ These sleep hygiene strategies were categorized into 5 key components (Table 1). The supplementary file includes a list of search terms in each database (Supplementary Methods). An author (GC) ran the search on July 18, 2024. The search was limited to English publications.

Table 1.

Search terms align with established sleep hygiene strategies

Key component	Sleep hygiene advice	Search terms
Sleep pattern or time	Go to bed/get up at around the same time every morning; aim for 7 to 8 h of sleep every night; limit time in bed to no more than 8.5 h.	sleep pattern, sleep schedule, sleep routine, sleep time, bedtime, wake time.
Bedtime activities	Avoid using a computer or other electronic screens within 1 h of bedtime; avoid exercising too late in the evening; Use relaxation techniques.	Exercise, relaxation, screen, computer, bedtime activity
Bedroom environment	Quiet, dark room with comfortable bedding and good temperature control; take the clock out of your bedroom.	Bedroom environment, comfortable bedding, temperature, clock, dark, bright light, quiet, noise
Alcohol, caffeine, and cigarette consumption	Alcohol, caffeine, and cigarettes: to be avoided for at least 4–6 h before going to bed.	Alcohol, caffeine, cigarettes, smoking, coffee, drinking
Daytime naps	If a nap is absolutely necessary, then limit this to about 20 mins. Make sure that you are awake for at least 4 h before going back to bed. Do not allow yourself to fall asleep in front of the TV.	Naps, daytime naps, napping

Data Extraction

Included studies were summarized in an extraction sheet developed based on the inclusion and exclusion criteria with the following key elements: (i) study design and country, (ii) population, (iii) intervention related to sleep hygiene, and (iv) outcomes. One author (GC) extracted the data and a second author (FY) reviewed it to confirm its accuracy and relevance. To answer the research question, we synthesized the sleep hygiene strategy findings into each component based on established recommendations (Table 1), with sleep hygiene education referring to the combination of all components.

Data Analysis and Synthesis

A statistical meta-analysis was performed using STATA (version 18)¹⁹ based on each component of the sleep hygiene strategy. Studies that have reported mean and SD for any sleep outcomes between intervention and control groups were included in the meta-analysis. Subgroup analyses were performed based on different CKD stages. Because of the substantial heterogeneity in how the sleep hygiene strategy is delivered (e.g., some use CBT, some use an educational approach to deliver sleep hygiene education), we performed subgroup analysis based on approaches. We calculated SMD with 95% CIs for continuous outcomes, using Hedges' g to account for small sample bias. If a study reported median and interquartile range instead of mean and SD, an estimated mean and SD were calculated using Wan et al.’s²⁰ method. The heterogeneity of the studies was analyzed using restricted maximum likelihood approach, presented by I² values, and if the I² > 50%, indicating substantial heterogeneity, a random effects model was employed.

Methodological Quality Assessment and Publication Bias

The methodological quality of systematic reviews was independently evaluated by 2 authors (GC and FY) using Hawker’s quality assessment tool for systematic reviews.²¹ This tool is particularly useful in systematic reviews where studies of varying designs and methodologies are included. The checklist comprises 9 questions; each question is scored as 4 (good), 3 (fair), 2 (poor), or 1 (very poor). Any disagreements among the reviewers were resolved through discussion. The total score ranged from 0 to 36, with higher scores indicating a better quality of evidence. Funnel plots and Egger's test were conducted using STATA to assess publication bias. A P-value < 0.05 was considered statistically significant for publication bias.

Results

Selection of Sources of Evidence

We identified 356 studies from the databases. After removing duplicates, 350 articles were screened based on title and abstract (by 2 authors GC and FY). The same authors reviewed 67 full-text articles independently based on eligibility criteria, and 38 met the criteria. In Figure 1, we present the PRISMA flow diagram for the study inclusion process.

Figure 1.

Flow diagram indicating selection of articles.

Characteristics of Sources of Evidence

The characteristics of included studies, based on the predefined data extraction sheet, including the following elements: study design or country, population, sleep hygiene strategy, outcomes or measures, and quality, are summarized in Table 2. The following sleep hygiene strategies were identified in the included studies (n refers to the number of studies): bedtime activities (n = 17); alcohol, caffeine, and cigarettes (n = 11), sleep hygiene education (n = 7), bedroom environment (n = 2), and sleep pattern or time (n = 1). Bedtime activities were predominantly evaluated with regard to exercise (n = 13) and relaxation techniques (n = 4) through quasi-experimental (n = 10) or randomized controlled trials (n = 5) designs, with only 2 observational studies. In contrast, studies that investigated sleep hygiene strategies regarding alcohol, caffeine, and cigarette use were all observational studies.

Table 2.

Characteristics of included studies

Study	Study design (country)	Population (number)	Sleep hygiene interventions	Measures	Findings	Conclusion	Quality
Bedtime activities Exercise
Aoike et al.22	RCT (Brazil)	CKD stage 3–4 (40)	Exercise: aerobic exercise (center group), walking (home group), no exercise (control group) Frequency: aerobic-30 mins with 10 mins increment every 4 wks till week 8 Timing: not reported	PSQI	Both exercise groups vs. control had a significant improvement in PSQI (P < 0.05, no effect size provided)	Home-based aerobic exercise was effective in improving the quality of sleep.	Fair
Yurtkuran et al.23	RCT (Turkey)	HD (37)	Exercise: Yoga-based exercise Frequency: Twice/wk for 12 wks Timing: Not reported	VAS	The exercise group had a higher percentage reduction in sleep disturbances than the control group (−25% vs. −5%, P = 0.04)	Yoga-based exercise may benefit sleep	Fair
Silva-Filho et al.24	RCT (Brazil)	HD (55)	Exercise: resistance training (combining 11 exercises) Frequency: 3× weekly for 12 wks Timing: intradialytic	Accelerometer	Exercise group improved sleep efficiency and sleep time compared with control (P < 0.05, no effect size provided)	Resistance training improves sleep quality	Fair
Barroso et al.25	RCT (South Korea)	HD (57)	Exercise: 3 exercise groups: aerobic exercise, resistance exercise, and combination exercise. Frequency: 3× weekly for 12 wks Timing: First 2 h of HD	Accelerometer	Sleep fragmentation index decreased significantly in aerobic (51.4 to 44.5, P = 0.03) and resistance exercise (52.3 to 40, P = 0.01) groups compared with baseline.	Intradialytic exercise may improve sleep quality.	Fair
Achmad et al.26	Quasi-experimental (Indonesia)	HD (38)	Exercise: stretch Frequency: 2× weekly for 8 wks Timing: intradialytic	PSQI IRSSG	Intradialytic stretch improved sleep quality (from 6.16 to 4.02, P < 0.001) and RLS (from 1.74 to 0.42, P < 0.001)	Intradialytic stretch decreases RLS and improves sleep quality.	Fair
Afshar et al.27	Quasi-experimental (Iran)	HD (28)	Exercise: stationary cycling Frequency: 3× weekly for 8 wks Timing: first 2 h of HD	PSQI	Exercise group improved sleep quality (from 12.14 to 6.29, P < 0.001). No decline in PSQI was found in the control group (from 11 to 12).	Aerobic exercise during the first 2 h of dialysis improves sleep quality.	Poor
Parent-Roberge et al.28	Pre- and post- (Canada)	HD (25)	Exercise: aerobic and resistance Frequency: 3× weekly for 6 mos Timing: first half of dialysis	PSQI	Exercise improved sleep quality (from 7.5 to 4.0, P = 0.035) postintervention.	Supervised intradialytic exercise benefits sleep quality in older patients	Fair
Mehta et al.29	Pre- and post- (India)	HD (30)	Exercise: walk Frequency: 5 d/wk for 2 wks Timing: evening	PSQI	Exercise group improved sleep quality (from 9.7 to 7.6, P = 0.001)	Exercise improves sleep quality	Very poor
Maniam et al.30	Pre- and post- (Malaysia)	HD (55)	Exercise: flexibility and strengthening Frequency: 3× weekly for 12 wks Timing: before dialysis	PSQI	The exercise group improved their sleep quality (from 10.1 to 7.6, P < 0.001); whereas the control group had increased PSQI, indicating worse sleep quality	Low to moderate exercise is effective for improving sleep quality	Fair
De Sousa Sa et al.31	Quasi-experimental (Brazil)	HD (52)	Exercise: resistance training Frequency: 3× weekly for 12 wks Timing: first 2 h of HD	PSQI	The exercise group has a higher percentage of patients with good sleep quality postintervention compared with the control group (68% vs. 31%, P = 0.2).	Intradialytic resistance exercise did not improve sleep quality	Poor
Elder et al.32	Observational (France, Germany, Italy, Japan, Spain, UK, US)	HD (11351)	Exercise: physical exercise Frequency: at least 1/wk Timing: not reported	KDQOL-SF-36	Exercise at least 1/wk is associated with lower odds of poor sleep quality compared with < 1/wk (AOR = 0.55–0.85, P < 0.05)	Physical exercise was associated with lower odds of poor sleep quality	Fair
Cho et al.33	Quasi-experimental (Brazil)	TX (20)	Exercise: aerobic exercise Frequency: 30–50 min Timing: not reported	PSQI	Exercise group had better sleep quality than the control group (4.14 vs 6.6)	Exercise improves sleep quality	Poor
Corrêa et al.34	Quasi-experimental (Brazil)	HD (14) TX (20)	Exercise: aerobic Frequency: 3× weekly Timing: not reported	PSQI	Compared with nonexercise groups, both HD and Tx exercise groups had better sleep quality (mean difference: −1.00 and −1.13 vs. 0.5)	Exercise improves sleep quality	Poor
Relaxation
Sleep Health Foundation35	RCT (Iran)	HD (86)	Relaxation: Benson’s relaxation technique Frequency: 2× daily for 8 wks Timing: not reported	PSQI	Relaxation group improved sleep quality (from 9.78 to 7.27, P < 0.0001), whereas control group had no changes (10.97 to 10.84, P > 0.05)	Benson’s relaxation technique improves sleep quality	Fair
Ebrahem et al.36	Quasi-experimental (Turkey)	HD (105)	Relaxation: foot reflexology and back massage. Frequency: 2 d/wk for 4 wks Timing: not reported	PSQI	Foot reflexology and back massage groups improved sleep quality (11.09 to 5.54, P < 0.001) and back massage groups (10.59 to 8.34, P < 0.001), not control group (9.20 to 11.88)	Foot reflexology and back massage improve sleep quality	Fair
Rambod et al.37	Quasi-experimental (Egypt)	HD (120)	Relaxation: Benson’s relaxation technique. Frequency: twice daily Timing: 2 h after the last meal	SQS	The relaxation group improved sleep quality in the relaxation vs. control group (28.43 vs. 44.55, P < 0.001).	Relaxation techniques enhance sleep quality	Fair
Unal and Balci Akpinar38	Quasi-experimental (Indonesia)	HD (50)	Relaxation: Muscle relaxation and aromatherapy. Frequency: 4 nights/wk for 3 wks Timing: not reported	ISI	Relaxation group, compared to the control group, had significant improvement in insomnia (7.68 vs. 10.12, P = 0.04)	Progressive muscle relaxation decreases insomnia	Fair
Alcohol, caffeine, and cigarettes
Rosdiana and Cahyati39	Observational (Taiwan)	HD (700)	Caffeine, alcohol, and cigarettes: Did not report amount/frequency/timing	PSQI, ESS, and Berlin questionnaire	Coffee consumption is associated with RLS (physician-diagnosed) (OR: 3.74, P = 0.001) and tea consumption is associated with sleep apnea (OR: 1.86, P = 0.01), but has no impact on insomnia.	Smoking was associated with sleep disorders. Caffeine was not associated with sleep quality.	Fair
Chen et al.40	Observational (Italy)	HD (694)	Cigarette, caffeine, and alcohol: unsure amount/frequency/timing	A sleep survey developed by authors	Cigarette smoking, caffeine, or alcohol intake, do not differ between the insomnia and noninsomnia groups (no effect size provided).	Alcohol, cigarettes, and caffeine were not associated with sleep disorders	Fair
Walker et al.41	Observational (Serbia)	HD (86)	Coffee: average 250 mg/d; Timing: morning and early afternoon	ESS and PSQI	Habitual coffee drinkers have less EDS (ESS > 10, 20.7% vs. 44.4%, 0.048) and insomnia (AIS score: 6.7 vs. 10.7, P = 0.01) compared with nonhabitual coffee drinkers; sleep quality was the same between the 2 groups (PSQI: 7.3 vs. 9.7, P = 0.12).	Caffeine was not associated with sleep quality.	Fair
Wang et al.42	Observational (Canada)	HD (54)	Coffee: > 2 cups of coffee Unsure timing	A sleep survey developed by authors	Coffee consumption (> 2 cups/d) is associated with more sleep-wake complaints than < 2 cups (no effect size provided)	Coffee consumption is associated with sleep-wake complaints.	Fair
Sabbatini et al.43	Observational (Taiwan)	HD (206)	Caffeine (tea drinking): Unsure amount/frequency/timing	PSQI	Tea drinking is an independent predictor of sleep quality (β = 0.20, P = 0.001)	Tea drinking habit was associated with sleep quality	Fair
Merlino et al.44	Observational (Italy)	HD (883)	Caffeine, alcohol, and cigarettes: Alcohol > 1 L/d	ESS and Hatoum’s sleep questionnaire	Sleep disorders (insomnia, RLS, OSAS: assessed by self-reported questionnaire, Belin and ESS) are associated with alcohol (OR: 8.69, P < 0.03) and cigarette use (OR: 1.49, P < 0.02), not caffeine.	Excessive alcohol intake and cigarette smoking were independent predictors of sleep disorders	Fair
Nikić et al.45	Observational (China)	HD (137)	Alcohol: unsure amount/frequency/timing	PSQI and IRLSSG	Habitual alcohol consumption (daily and regularly) is an independent risk factor for RLS (OR: 4.72, P = 0.02)	Alcohol consumption was a risk factor for RLS.	Fair
Holley et al.46	Observational (US)	PD (81)	Cigarette, caffeine, and alcohol: Unsure amount/frequency/timing	A sleep survey developed by authors	Alcohol and smoking are not related to sleep complaints (no effect size provided).	Alcohol, cigarettes, and caffeine were not associated with sleep problems	Fair
De Vecchi et al.47	Observational (US)	HD (48) PD (22) Healthy controls (41)	Caffeine and cigarettes, napping: Coffee > 1 cup/d	A sleep survey developed by authors	Caffeine intake is associated with reported sleep disturbances (percentage of people reported caffeine intake in sleep disorder vs. no sleep disorder group: 72% vs. 56%, P = 0.05).	Caffeine intake was associated with sleep disturbances	Fair
Williams et al.48	Observational (Italy)	HD (87) PD (84)	Caffeine and cigarettes: did not report amount/frequency/timing	A sleep survey developed by authors	No statistical difference in the percentage of PD and HD patients reported sleep disorders and intake of caffeine and cigarettes	Caffeine and cigarettes were not associated with sleep disorders	Poor
Lin et al.49	Observational (US)	Pre-TX (25) TX (30)	Coffee: unsure amount/frequency/timing	Polysomnography and sleep diary	Less amount of coffee consumption predicts less total sleep time (no effect size provided)	Coffee consumption is associated with sleep disturbances.	Fair
Sleep Pattern/Time
Shibata et al.50	Observational (Japan)	HD (24) Healthy controls (24)	Sleep regularity: unsure of the timing of regularity regarding bedtime, wake time or both	Lifestyle recording device	HD patients had lower intensity of sleep-wake cycles (0.05 vs. 0.07, P < 0.05) in 24 h due to irregular sleep-wake cycles, and is significantly correlated with sleep efficiency, sleep latency and wake after sleep onset	A regular sleep pattern may improve sleep quality.	Fair
Bedroom environment
Burkhalter et al.51	Pilot RCT (Switzerland)	Tx (30)	Bright light therapy: morning light therapy 30 min/d × 3 wks.	Actimeter	Bight light improved sleep latency (from 21 min to 18 min) and sleep efficiency (from 76% to 78%)	Bright environments may synchronize circadian rhythms and improve sleep.	Fair
Stepanski et al.52	Single-case experimental (Sweden)	PD (9)	Sleep environment + sleep hygiene education: pressure-relieving mattress for 4 wks.	Actigraphy and sleep diary	3 out of 5 patients who attended mattress intervention reported sleep improvement	Nonpharmacological interventions can improve sleep	Fair
Sleep hygiene education
Chen et al.53	RCT (Iran)	HD (82)	CBT: 6× weekly sessions, 30 min/session, face-to-face training vs. no CBT	PSQI	CBT group improved sleep quality (9.92 vs. 13.05, P = 0.001) in the intervention vs. control group.	The sleep hygiene training program improved the sleep quality.	Fair
Chen et al.54	RCT (Turkey)	HD (67)	Sleep hygiene education: 1/wk × 3 wks 20 min/session vs. no sleep hygiene education	PSQI	Sleep hygiene group improved sleep quality 5.51 vs. 12.63, P < 0.001) in the intervention vs. control group.	The sleep hygiene training increased sleep quality.	Fair
Saeedi et al.55	RCT (China)	HD (103)	CBT: 3× weekly, 20 min/session, face-to-face training vs. no CBT	PSQI	CBT group improved sleep quality (12.6 vs. 16.4, P < 0.0001) in the intervention vs control group.	Sleep behavior modification in combination with muscle relaxation effectively improved sleep quality	Poor
Park et al.56	RCT (Taiwan)	HD (72)	CBT: 6x tri/weekly sessions, 30 min/session vs. sleep hygiene education.	PSQI	Both groups improved sleep quality (CBT group from 13.4 to 9.9, P ≤ 0.001; control group: 12.2 to 11.6, P = 0.04), but more in the CBT than control group (9.6 vs. 11.8, P < 0.001)	CBT is effective in correcting disorganized sleep patterns	Fair
Hou et al.57	RCT (Taiwan)	PD (24)	CBT: weekly x 4 wks, 60 min/session v.s sleep hygiene education.	PSQI	CBT may improve sleep quality (median percentage change: −14.3 vs −1.7, P = 0.3) in the intervention vs. control group.	CBT may be effective in improving sleep quality	Fair
Muz et al.58	Quasi-experimental (Turkey)	HD (80)	Sleep hygiene education: 3 sessions, 40–60 min/session during dialysis, face-to-face vs. no sleep hygiene education	PSQI	Intervention group improved sleep quality (12.05 to 10.85 P = 0.001).	Sleep hygiene education improves sleep quality	Fair
Ebrahimi et al.59	Pre- and post- (South Korea)	HD&PD (17)	CBT: 9× tri-weekly sessions, 30 min/session, online self-directed training	PSQI	CBT improved sleep quality (11 vs. 5, P < 0.001), pre- vs postinterventions.	CBT improves sleep quality	Fair

AIS, Athens Insomnia Scale; ARO, adjusted odds ratio; CBT, cognitive behavior therapy; EDS: excessive daytime sleepiness; ESS, Epworth Sleepiness Scale; HD, hemodialysis; ISI, Insomnia Severity Index; IRLSSG, International Restless Legs Syndrome Study Group; KDQOL-SF-36, Kidney Disease Quality of Life Short Form; OR, odds ratio; OSAS, Obstructive Sleep Apnea Syndrome; PSQI, Pittsburgh Sleep Quality Index; PD, peritoneal dialysis; RCT, randomized control trial; RLS, restless leg syndrome; SQS, Sleep Quality Scale; TX, transplantation; VAS, Visual Analog Scale.

The CKD populations included individuals undergoing maintenance HD (n = 27), peritoneal dialysis (PD, n = 3), HD and PD (n = 3), had a kidney transplant (n = 3), HD and transplant (n = 1), and CKD stages 3 to 4 (n = 1).

Methodological Quality and Publication Bias

The overall quality of all studies was fair, with a median (interquartile range) score of 3.7 (3.1–3.9). However, there was substantial heterogeneity in the study quality across the studies (Table 2). The most common issues identified were a lack of discussion on sampling strategies, with 9 studies (24%) having insufficient details on sampling strategies. Other concerns included a lack of discussion on the transferability of the findings and implications for policy and practice. A summary of the methodological quality of each criterion from the included studies is presented in Figure 2. The funnel plot showed that studies were evenly distributed (Supplementary Figure S1), and the Egger’s regression test indicated no significant asymmetry (P = 0.18), suggesting no evidence of publication bias for sleep hygiene strategy. Egger’s test was not conducted for each sleep hygiene strategy because of the small number of studies.

Figure 2.

A summary of the methodological quality of each criterion from the included studies.

Overall Sleep Hygiene Strategy

The meta-analysis demonstrated that the sleep hygiene strategy overall had a significant effect on sleep quality (SMD: −1.11, 95% CI: −1.58 to −0.63, I²: 91.3%). Subgroup analysis showed that among sleep hygiene strategies, relaxation (SMD: −1.54, 95% CI: −2.34 to −0.73, I²: 91.8%)) had the most significant effect on sleep quality, followed by exercise (SMD: −1.05, 95% CI: −2.03 to −0.07, I²: 87.8%) and sleep hygiene education (SMD: −0.82, 95% CI: −1.57 to −0.08, I²: 92.4%) (Figure 3).

Figure 3.

Forest plot showing the effects of sleep hygiene strategies compared with usual care on changes in sleep quality. CI, confidence interval; F, foot massage; HD, haemodialysis; R, relaxation; SMD, standard mean difference; Tx, transplantation.

Bedtime Activities

Exercise and relaxation were the most frequently assessed sleep hygiene strategies within the range of bedtime activities. Thirteen studies (45%) investigated the effect of exercise on sleep. All but 3 studies (1 on patients with CKD stages 3 to 4²² and 2 on patients with a kidney transplant^24,25) included populations other than patients on HD. The pooled effect of exercise was calculated from 5 studies (1 randomized controlled trial²³ and 4 quasi-experimental24, 25, 26, 27) that reported effect size, revealing a significant improvement in sleep quality (SMD: −1.05, 95% CI: −2.03 to −0.07, I²: 87.8%), measured subjectively by using PSQI and Visual Analogy Scale (Figure 4). When results were stratified by CKD stages, the pooled effect was not significant, as indicated by the small number of studies (HD: 4 studies, transplant: 2 studies) (Figure 4). Of the 2 studies that used accelerometers to report objective sleep quality, Cho et al.³³ found that patients on HD who were randomly assigned to the aerobic exercise and resistance exercise group improved their sleep fragmentation index, indicating better sleep quality, compared with the baseline (aerobic exercise: 51.4 vs. 44.5, P = 0.03; resistance exercise: 52.3 vs. 40, P = 0.01). Similarly, Correa et al.³⁴ used 11 different exercises for resistance training during dialysis and found that the intervention group showed improved sleep efficiency and duration compared with the control group; however, the effect size was not reported. Sleep hygiene advice suggests avoiding exercising too late in the evening.³⁵ There was heterogeneity among studies regarding types of exercise, timing and frequency. In these studies, exercises were performed either before or during HD treatment; because of the varying dialysis shifts in dialysis units worldwide, the exact timing could not be determined in these studies.

Figure 4.

Forest plot showing the effects of exercise compared with usual care on changes in sleep quality. CI, confidence interval; HD, haemodialysis; SMD, standard mean difference; Tx, transplantation.

Four studies (11%) investigated the effect of relaxation techniques and sleep in the HD population. The meta-analysis demonstrated a significant effect of relaxation on the improvement of sleep quality (SMD: −1.54, 95% CI: −2.34, −0.73, I²: 91.8%) (Figure 3). These studies concluded that relaxation using Benson’s relaxation technique,^36,37 foot reflexology and back massage,³⁸ and muscle relaxation and aromatherapy³⁹ improved self-reported sleep quality. The subgroup analysis demonstrated a significant effect for each relaxation strategy; however, this evidence was derived from a small number of studies with high heterogeneity (I²: 91.8%) (Figure 5). Sleep hygiene recommendation³⁵ advises using relaxation techniques in the evening before bedtime to relax and wind down. Only 1 study³⁶ reported the timing of the intervention and concluded that practicing relaxation 2 hours after the last meal significantly improved self-reported sleep quality as measured by the sleep quality scale (mean score postintervention in the intervention vs. control: 28.43 vs. 44.55, P < 0.001).

Figure 5.

Forest plot showing the effects of relaxation compared with usual care on changes in sleep quality. NA, not applicable; CI, confidence interval; SMD, standard mean difference.

Alcohol, Caffeine, and Cigarettes

Nine observational studies (24%) investigated the relationship between caffeine consumption and sleep in patients with CKD. Because of the heterogeneity of data reporting among these studies, the results are summarized narratively. Of the 6 studies that focused on patients on HD, conflicting effects of caffeine consumption were observed. A large cohort study in Taiwan (n = 700 patients on HD)⁴⁰ reported that coffee consumption increased the likelihood of restless leg syndrome (odds ratio [OR]: 3.74, P = 0.001), and tea consumption increased the risk for sleep apnea (OR: 1.86, P = 0.01). Similarly, 2 other observational studies disclosed that caffeine consumption (> 2 cups of coffee/d⁴¹ and tea drinking⁴²) are associated with poorer self-reported sleep quality. In contrast, 2 large cohort studies in Italy (n = 694 patients on HD⁴³ and n = 883 patients on HD⁴⁴) reported no statistical association between caffeine intake and self-reported insomnia or sleep disorders. Interestingly, Nikic et al.⁴⁵ found that habitual coffee drinkers (those who consume more than 1 cup of coffee daily) reported less insomnia (measured by Athens Insomnia Scale) than non–coffee drinkers in a sample of 86 patients on HD (Athens Insomnia Scale score: 6.7 vs. 10.7, P = 0.01). For both HD and PD patients, Holley et al.⁴⁶ found that fewer patients on dialysis reported consuming > 1 cup of coffee/d compared with healthy controls (50% vs. 83%, P = 0.005), and caffeine intake (including coffee and tea) is associated with increased self-reported sleep disturbances (percentage of people reported caffeine intake in sleep disorder vs. without sleep disorder group: 72% vs. 56%, P = 0.05); however, this is in contrast with De Vecchi et al.’s⁴⁷ study, where they found no association between caffeine and sleep disorders in a group of HD and PD patients. Only 1 study focused on transplant patients⁴⁸ and found that less caffeine consumption was associated with less total sleep time (measured by polysomnography and sleep diary) in a sample of 30 post–kidney transplant patients. The principle of sleep hygiene is to avoid caffeine consumption at least 4 to 6 hours before bedtime, because caffeine, being a stimulant, can keep people awake.³⁵ The timing of caffeine consumption is not reported in these observational studies.

The effect of alcohol and cigarette smoking was investigated in 4 observational studies (11%) with mixed findings. Consistent negative effect of alcohol on sleep disorders were observed in patients on HD. Lin et al.⁴⁹ reported that among 137 patients on HD, the risk of restless leg syndrome increased significantly in those who drink alcohol daily (OR: 4.72, P = 0.02). Similarly, in a large cohort of Italian patients on HD,⁴⁴ self-reported sleep disorders, including insomnia, restless leg syndrome and sleep apnea, are significantly associated with alcohol use (OR: 8.69, P < 0.03) and cigarette use (OR: 1.49, P < 0.02). In contrast, 2 studies in a small cohort of patients on PD and a combination of PD and HD patients (n = 81 patients on PD; and n = 87 patients on HD and n = 84 patients on PD) found no association between alcohol use⁵² and cigarette smoking^47,52 and self-reported sleep complaints.

Sleep Hygiene Education

Seven studies (18%), mostly randomized controlled trials (n = 5) in patients on HD (n = 5), reported the effect of sleep hygiene education. The pooled analysis of 6 studies in all patients on dialysis showed a significant positive effect of sleep hygiene education on sleep quality (SMD: −0.82, 95% CI: −1.57 to −0.08, I²: 92.4%). We did not stratify data based on dialysis modality because there was only 1 study that reported the PD data separately. Chen et al.⁵³ found that in a group of 24 patients on PD, those who received CBT reported a significant improvement in sleep quality, as indicated by a reduction in PSQI scores (mean percentage change in PSQI: −14.3%), whereas patients who received only sleep hygiene education showed lesser improvement (mean percentage change in PSQI: −1.7). The same researchers conducted a similar trial in a cohort of 72 patients on HD⁵⁴ and found that both CBT and sleep hygiene education had a positive effect on sleep quality, as demonstrated in a statistically significant reduction of PSQI postintervention; however, the CBT group reported better sleep quality than the control group (mean PSQI in CBT vs. control: 9.6 vs. 11.8, P = 0.001). The implementation of sleep hygiene education varied across studies: some were embedded as part of the CBT,53, 54, 55, 56, 57 whereas others used educational approaches.^58,59 When stratifying results based on the delivery approach, embedding sleep hygiene education as part of the CBT had a significant effect on sleep quality (SMD: −0.77, 95% CI: −1.44 to −0.10) than using the educational approach alone (SMD: −0.98, 95% CI: −3.32 to 1.36) (Figure 6).

Figure 6.

Forest plot showing the effects of sleep hygiene education compared with usual care on changes in sleep quality.CBT, cognitive behaviour therapy; CI, confidence interval; SMD, standard mean difference.

Limited Evidence Found

There was limited information on napping, screen time, and computer use during bedtime activities. There was also limited and inconclusive evidence regarding sleep patterns⁵⁰; bedroom environment, including bright light⁵¹; and pressure-relieving mattress.⁶⁰

Discussion

This review assessed the evidence on sleep hygiene strategies for patients with CKD. The main goal was to identify the applicability of sleep hygiene strategies in the CKD population. Overall, sleep hygiene strategies, particularly those incorporating exercise and relaxation techniques, show promise. There is limited evidence on the effects of napping and environmental factors such as light and bedroom comfort, indicating a need for further research. Maintaining good sleep habits enhances better sleep and overall health and is considered important to patients with CKD. How to tailor these strategies for individuals with CKD by considering available evidence and treatment-related factors, such as dialysis schedules and diet or fluid restrictions, is an area requiring further research.

Exercise is one of the most frequently investigated sleep hygiene strategies to date. Sleep hygiene recommendations generally advise against late evening exercise, and evidence for this practice in patients with CKD, particularly those undergoing maintenance dialysis, often involves exercise either before or during dialysis sessions. Given the constraints of dialysis schedules on lifestyle, incorporating exercise into evening sessions for those who receive regular dialysis in the evening might be a practical approach. The Kidney Disease: Improving Global Outcomes CKD clinical practice guideline recommends that patients with CKD undertake regular exercise, compatible with cardiovascular and physical tolerance, aiming for at least 150 minutes/wk.⁶¹ The guideline recommendations do not specify the timing of exercise. A recent review suggested that correctly timed exercise could be a therapeutic tool for ameliorating sleep disturbances, potentially related to its effect on circadian rhythms.⁶² In CKD, circadian rhythms can be disrupted due to uremic toxins,¹⁷ whereas additional factors such as increased inflammation and sleep disturbances further interfere with the body’s internal clock. Our review demonstrated that exercise may improve sleep quality, although the effect was not significant when data were stratified by different stages of CKD. This may be because of the small sample sizes in each group, as well as inconsistencies in the type, timing, and frequency of exercise reported in the current studies. Given the importance of exercise in relation to sleep quality, future research should investigate the optimal type, timing, and frequency of exercise to enhance the applicability of sleep hygiene strategies for improving sleep quality in individuals with CKD.

Relaxation techniques are known for their simplicity and cost-effectiveness in alleviating depression, worry, and stress,⁶³ all of which are established contributors to insomnia.⁶⁴ In patients with CKD, psychological distress, including depression and anxiety, is common.⁶⁵ Our findings support the notion that various relaxation techniques have positively impacted sleep quality in this population. Incorporating these techniques into health education for managing insomnia can be beneficial, given their ease of implementation.

Avoiding cigarette smoking, caffeine, and alcohol is recommended for promoting sleep hygiene. Smoking is a well-known risk factor for CKD⁶⁶; but the relationship between alcohol consumption and CKD has been inconsistent. Recent studies suggest a U-shape relationship between alcohol consumption and the risk of CKD.^67,68 Our findings revealed that alcohol consumption is associated with sleep disorders; however, the amount of alcohol is not reported in these studies. We also reveal mixed results regarding the impact of caffeine on sleep. Given that patients with CKD already face strict dietary and fluid restrictions, introducing additional restrictions on alcohol and caffeine without evidence-based support from the literature can exacerbate adherence and potentially lead to noncompliance. Further research is needed to better understand the effects of alcohol and caffeine consumption, including optimal timing and quantity, to refine recommendations for these patients.

Interestingly, existing studies rarely investigate the impact of napping on sleep in patients with CKD. Although Sabbatini et al.⁴³ reported that most patients who experienced sleepiness took naps during the day; the relationship between daytime napping and sleep has not been analyzed. Napping is common among patients undergoing maintenance dialysis and is often believed to be an insomnia contributor in this population.⁶⁹ A systematic review of qualitative studies found that though patients are aware of the negative impact of napping on sleep and attempt to avoid napping, the early dialysis schedules often cause fatigue and precipitate daytime napping.⁷⁰ Sleep hygiene recommendations advise avoiding naps longer than 30 minutes and within 4 hours of bedtime.³⁵ Future studies should assess the effect of napping on individuals with CKD, because this practice is not uncommon among this population.

This review provides evidence supporting the use of sleep hygiene strategies to manage insomnia in individuals with CKD. Our findings can help inform clinicians that the advice given to people with CKD experiencing insomnia and poor sleep is evidence-based and may improve their sleep quality. However, it is important to note that people with CKD, particularly those with end-stage kidney disease, are commonly affected by sleep disorders such as sleep apnea and restless legs, which can further impact sleep quality.⁷¹ Therefore, sleep hygiene strategy alone may not be sufficient to improve sleep. Screening and managing coexisting sleep disorders, alongside implementing sleep hygiene strategies, should be considered an important part of the treatment plan for this population. Despite the advantages of this study, including its rigorous approach to developing search terms based on an established sleep hygiene strategy recommended by professional bodies, several limitations must be acknowledged. First, whereas the search terms were developed based on established sleep hygiene strategies and were further broadened to include sleep habits, terminologies used in the literature tended to be inconsistent, and it is possible that relevant articles could have been missed. Second, we did not include the “grey” literature such as newsletters, reports, or media; and non-English articles, which may have resulted in missing studies. In addition, the heterogeneity of methodology in the selected studies made synthesizing difficult, which may influence the result analysis.

Conclusion

This review indicates that CBT, incorporating sleep hygiene education, can be an effective approach to improving sleep quality in individuals with CKD. Although exercise and relaxation techniques may help reduce sleep disturbances, additional research is required to establish the best timing for these activities. Existing studies have methodological limitations and highlight gaps in research, particularly in areas such as daytime napping, which is common among individuals undergoing dialysis treatments. These limitations and gaps need to be addressed to better understand the applicability of sleep hygiene strategies for the CKD population.

Disclosure

AV is the associate editor of Kidney International Report and has received speaker honoraria from CSL Seqirus and Alexion. All the other authors declared no competing interests.

Supplementary Material

Supplementary File (PDF)

Supplementary Methods. Figure S1. Funnel Plot of sleep hygiene strategy studies included in meta-analysis. PRISMA Checklist.