Impact of school start time and sleep pattern of adolescents on their mood and sleep quality

Abstract

Objective:

The physiological delay in bedtime among adolescents, compounded with the early start of school, results in insufficient sleep, especially on school days. The present study compared the sleep pattern and moods of students attending two schools with different start timing.

Materials and Methods:

The study involved adolescents from two schools with different start times: School A (7 am) and School B (8 am). Pittsburgh Sleep Quality Index, Depression Anxiety Stress Scales-21, and Pediatric Daytime Sleepiness Scale questionnaires were used to assess students’ mood, sleep duration, sleep quality, and daytime sleepiness. The clinical trial registry number is CTRI/2022/06/043556.

Result:

A total of 640 students (mean age 13.7 ± 2.0 years; 47.5% male) participated in this study. Students from School B had longer sleep duration, with 72.9% reporting sleep deprivation compared to 87.1% of School A (P = 0.00001). School A students reported having (P ≤ 0.001) higher daytime sleepiness, higher daytime dysfunction (P = 0.023), and poorer sleep quality. Students at School A scored higher for all mood derangements, with significantly higher scores for depression (P = 0.041).

Conclusion:

The study illustrates that though not much differences are observed in the bedtime of adolescents of the two schools, however, due to the early school start time of School A, students have to compulsorily wake up early, leading to higher sleep deprivation and greater mood derangements among them.

Introduction

Sleep is a fundamental human necessity that profoundly affects many cognitive, emotional, and performance-related processes. For adolescents to function at their best, 9:25 hours of sleep per night is recommended.[1] Despite this, many adolescents obtain less than the required amount of sleep leading to sleep debt.[2] In a survey, the average sleep time of adolescents residing in and around Paris was found to be 7:14 hours.[3] Teens in the United States have been reported to lag by 90 minutes on their required amount of sleep every night.[4] South Korean adolescents hold the title of being “most sleep deprived,” with an average sleep of 4.9 hours per night.[5] Japanese adolescents, though, share an identical academic environment to that of South Korea and have reported better sleep hours of 7.2–7.8 per night. Parental demands from their children to excel in academics/sports were found to be one of the major causative factors of this difference among South Korean adolescents.[5] Indian adolescents face similar challenges and have an average sleep of 7:21 hours at 11 years of age to 6:48 hours at 15 years.[6] Thus, demonstrating an increase in sleep loss with age among adolescents.[4]

Worldwide, surveys have demonstrated that as adolescents get older, they stay up late on school as well as non-school nights but wake up late, especially on weekends or holiday mornings.[4,6-9] Persistent weekday–weekend irregularity not only interrupts the sleep/wake cycle but further worsens adolescent chronological phase delay leading to alertness deficit in varied aspects.[10] This weekly sleep loss is not only associated with increased daytime sleepiness, napping, and compensatory oversleep behavior on weekends but has an impact on the behavior, poor decision-making, shortened attention span, depression, risk-taking behavior, and poor performance of our youngsters.[2,9,11]

A concomitant behavioral shift from bedtime to a delayed time frequently occurs together with the transition through adolescence.[4] Physiological delay in sleep/wake rhythm during adolescence due to a slower buildup of homeostatic sleep drive added to the behavioral postponement of sleep during puberty can lead to circadian delayed sleep phase syndrome (DSPS).[12] The incidence of DSPS among adolescents is 7.3% worldwide.[13] This developmental pattern is also influenced by societal factors, including a decline in parental control over their children’s sleeping habits, more social activities at night, online socializing, higher academic pressure, etc.[9,12,14] Knowledge and awareness among the society, students, parents, and primary physicians about the detrimental effects of sleep loss on performance and physical and mental health can play a preventive role. Thus, it becomes crucial to comprehend the effects of insufficient sleep and the major elements affecting adolescents’ sleep patterns since they represent the future of our society.

Numerous studies explored the effects of sleep deprivation on mental and physical productivity in students. To add to the growing evidence, the present study vitally focuses on investigating how delayed bed timings in association with an hour difference in school start timings impacts sleep duration, sleep quality, daytime sleepiness, and mood of adolescents.

Materials and Methods

Study design

A cross-sectional study was conducted among the students of two schools identified with different school timing, School A with a school start time of 7 am and School B with a school start time of 8 am. The study was conducted in accordance with the Declaration of Helsinki and after obtaining approval from the Institutional Ethics Committee. After obtaining prerequisite permission from school administrations, adolescents belonging to grades 6–12 were introduced to the study and were invited to participate. The study is registered in the Clinical Trial Registry India (CTRI/2022/06/043556).

Procedure

Details about their sleep habits and mood were obtained through the administration of standardized questionnaires. Explanations were provided in readily understandable language for each item on the questionnaires, as and when required. Students on any long-term medicine for epilepsy, attention-deficit hyper disorder, and pulmonary disease were excluded from the study. The following questionnaires were administered to only those students who willingly gave their assent for participation and submitted their parental consent for the same.

Pittsburgh sleep quality index (PSQI)

PSQI, a 19-item, self-reported questionnaire, was used to estimate sleep quality and disruption during the previous month. It contains seven components, including sleep duration, sleep disturbance, sleep onset latency, daytime dysfunction, sleep efficiency, sleep quality, and usage of sleep medicine. Each component is scaled on a 4-point Likert scale of 0–3, and the total PSQI scores ranged from 0 to 21, with scores >5 indicating poor sleep quality.[15]

Paediatric daytime sleepiness scale (PDSS)

PDSS has eight-item self-report questions providing an assessment of daytime sleepiness among school-age children and adolescents. Each item is marked on a Likert scale of 0–4 with a total score ranging from 0 to 32. Higher scores signify greater daytime sleepiness among adolescents.[16]

Depression anxiety stress scale (DASS-21)

DASS-21 is used to assess depression, anxiety, and stress-related emotional states. On this scale, 21 items range from “did not apply to me at all” to “applied to me very lot, or most of the time,” with “0” signifying “did not apply to me at all.” There are seven questions each for the assessment of depression, anxiety, and stress, and higher scores indicate a higher grade in that particular emotional state.[17]

Statistical method

Data were entered using Microsoft Excel and statistical analysis was done using SPSS version 22 (Statistical Package for Social Sciences, Inc., Chicago, IL, USA). Descriptive statistics for all continuous variables are expressed as mean ± SD and as percentage (N) for categorical variables. Independent sample t-test, the Chi-square test, and one-way analysis of variance were used to compare differences between groups. Correlation analysis between two numerical variables was performed using Spearman correlation. All statistical tests used a confidence interval of 95%, two-tailed, and probability (P) value <0.05 to determine if an effect was statistically significant.

Result

A total of 304 male and 336 female adolescents aged 11–18 years participated in the study. Out of the total participants, 256 students were from School A (school start timing 7 am) and 345 students were from School B (school start timing 8 am).

Sleep patterns of the students

Sleep routines of students at both schools were comparable [Table 1]. 31.10% of students at School A and 26.90% students of at School B went to bed before 10 pm on weekdays and there was no significant difference in sleep patterns of the two groups on weekends. However, 59.50% of students at School A reported waking up before 6 am (P = 0.007); thus had significantly less (P = 0.012) total sleep duration (6:24 ± 1:08 hours) as compared to 48.7% of students at School B who reported comparatively longer total sleep duration (6:53 ± 0:59 hours). Thus, a higher number of students at School A were sleep-deprived (P < 0.001). Grade-wise comparison too showed that students in School A had less sleep duration. However, the students of classes 10 and 12 of both schools were able to receive comparatively lesser total sleep duration compared to other classes [Figure 1]. School A students also reported having significantly (P ≤ 0.001) higher daytime sleepiness, higher daytime dysfunction (P = 0.023), and poorer sleep quality for all the classes [Table 1, Figure 2]. Sleep onset latency was higher among School A students compared to that of School B (P = 0.006).

Table 1.

Comparison of sleep patterns of the students of two schools (n=640)

Variables	School A	School B	P
Bedtime before 10 pm
Weekday	31.10% (82)	26.90% (101)	0.247
Weekend	13.60% (36)	16.50% (62)	0.324
Wake-up time before 6 am
Weekday	59.50% (157)	48.70% (183)	0.007*
Weekend	9.50% (25)	9.00% (34)	0.854
Total sleep duration	06:24±1:08	06:53±0:59	0.012*
Sleep deprivation (sleep <8 h)	87.10% (230)	72.90% (274)	<0.001*
Sleep quality (PSQI score >5)	38.60% (102)	35.90% (135)	0.481
Daytime sleepiness	13.70±5.58	11.89±5.61	<0.001*
Sleep disturbance	1.13±0.580	1.11±0.625	0.629
Sleep latency	1.09±0.804	0.92±0.740	0.006*
Daytime dysfunction	1.00±0.937	0.84±0.665	0.023*

*P>0.05 is significant

Figure 1.

Comparison of total sleep duration of the students of classes 6 to 12 of School A and B

Figure 2.

Comparison of means of sleep quality of the students of class 6 to 12 of School A and B

Mood of the students

Students at School A showed higher mood derangements and scores were significantly higher among them for depression (P = 0.041) [Table 2]. More students from school reported having mild to extremely severe depression, anxiety, and stress (41.3%, 48.9%, and 22.7%, respectively) compared to students of School B (35.1%, 41.8%, and 16.5%, respectively) [Figure 3]. On grade-wise comparison, mood scores for students of classes 10 and 12 of two schools were observed to be maximum for all three states, and it was highest for School A students [Figures 4–6].

Table 2.

Comparison of the status of mood of the students of two schools (n=640)

School	Mean±SD	P
Depression
School A	8.95±8.03	0.041*
School B	7.07±6.90
Anxiety
School A	8.61±8.02	0.078
School B	7.02±7.11
Stress
School A	9.24±7.83	0.318
School B	7.40±7.03

*P>0.05 is significant

Figure 3.

Comparative status of mood derangements among the students of two schools

Figure 4.

Comparison of depression scores of the students of classes 6 to 12 of School A and B

Figure 6.

Comparison of stress scores of the students of classes 6 to 12 of School A and B

Figure 5.

Comparison of anxiety scores of the students of classes 6 to 12 of School A and B

Association of mood with sleep parameters

All three states of mood (depression, anxiety, and stress) showed a significantly positive (P ≤ 0.001) correlation with all sleep parameters, i.e., sleep quality, daytime sleepiness, sleep latency, sleep disturbance, and daytime dysfunction scores except total sleep duration, which showed a significant negative correlation (P = 0.017) with depression [Table 3].

Table 3.

Correlation analysis between sleep variables and mood of the adolescents

	Depression (n=640)	Anxiety (n=640)	Stress (n=640)
Total sleep duration
r	−0.095	−0.077	−0.072
P	0.017*	0.051	0.067
Sleep quality
r	0.355	0.363	0.339
P	<0.001**	<0.001**	<0.001**
Daytime sleepiness
r	0.226	0.209	0.229
P	<0.001**	<0.001**	<0.001**
Sleep latency
r	0.230	0.202	0.194
P	<0.001**	<0.001**	<0.001**
Sleep disturbance
r	0.266	0.312	0.262
P	<0.001**	<0.001**	<0.001**
Daytime dysfunction
r	0.283	0.284	0.234
P	<0.001**	<0.001**	<0.001**

**Existence of a very strong correlation which is significant at the 0.01 level (two-tailed). *Correlation is significant at the 0.05 level (two-tailed)

Bedtime and its association with sleep parameters

Significant (P = 0.021) differences were observed in the total sleep duration of the students sleeping before and after 11 pm on weekdays [Figure 7]. A steep rise in PSQI score (P = 0.002) was noted with the delay in bedtime from 10 to 11 pm to later than 12 am on weekdays [Figure 8]. It was also noted that students sleeping late (after 10 pm) registered greater daytime sleepiness (P = 0.019) compared to those sleeping before 10 pm [Figure 9].

Figure 7.

Effect of delayed bedtime on total sleep duration of students

Figure 8.

Effect of delayed bedtime on sleep quality of students

Figure 9.

Effect of delayed bedtime on daytime sleepiness of students

Discussion

The present study explored the effect of school timings in addition to the physiological sleep pattern of adolescents on total sleep duration, sleep quality, and mood of students of grades 6–12. With increasing grades, adolescents tend to stay up late but as their wake-up time was governed by their school timings, the total sleep duration of students having early school (School A) was more compromised compared to students at School B with later school timings. A higher number of students at School A registered mood derangements; they also had higher scores for depression, anxiety as well as stress. Even the sleep quality deteriorated with the delay in bedtimes of the students.

Our study revealed that, regardless of the wake-up time, almost 70% of students of both schools slept after 10 PM on weekdays. In spite of delayed bedtime, students of School A were obligated to wake up early due to early bell timings, which led to a decrease in total sleep duration [Table 1]. Numerous studies have reported that early school timings significantly limit the number of hours available for sleep.[7,8,18,19] Studies have specified that students with school start time at 7:30 am or earlier get a shorter duration of sleep on school nights.[18,19] Additionally, Carskadon et al., in their study, found that weekday bedtime significantly correlated with pubertal stage both in boys as well as girls, with later bedtimes reported by students having higher scores on the pubertal scale.[14] In the present study, we enrolled students from two schools with a difference in school start time of greater than 1 hour; however, the physiological shift in bedtime associated with pubertal changes could not be assessed.

Adolescents of both the schools in the present study slept for longer duration on weekends with later bedtime as well as wake up schedule. Similar results were observed by Szymczak et al., among the Polish students aged 10 and 14 years, who slept for longer duration on weekends/holidays, due to no compulsory wake-up schedule on non-school days.[20] Singh et al., too have observed a delay in bedtime on weekends in both preteens and teenagers, with teenagers having a significantly greater delayed bedtime.[6] Thus, students’ wake-up timings are primarily determined by their school start timings.[20] Students of School A fell short of 30 minutes in total duration of sleep compared to students of School B (P = 0.012). However, the average total duration of sleep among adolescents in both schools was less than 7 hours on school nights, which is less than the optimum amount of sleep.[1] Several studies globally have shown that on average adolescent gets about 6.8 hours of sleep on school night, leading to sleep deprivation.[1,3,21] Greater number of students of School A (38.60%; 102) had PSQI >5; 87% of students of School A were sleep deprived (P = 0.001); School A students registered higher daytime dysfunction (P = 0.023), daytime sleepiness (P ≤ 0.001), and greater sleep onset latency [Table 1]. Dubey et al. have shown that a higher number of students (9.3%) had PSQI score >5 on school days compared to only 6.5% students during vacations.[22] A study has shown that more than 27% of adolescents admitted to falling asleep during the first hour of class.[1] A majority of research on adolescent sleep patterns reveals a trend of reduced overall sleep time, a propensity to sleep later, and an elevated level of daytime sleepiness.[23] Hence, early school start time may be one of the powerful contributors to this issue, but a behavioral change in the sleep schedule of adolescents needs to be supervised and implemented to prevent sleep deprivation and its consequences among them.

Mood and its association

Students of School A were significantly more depressed and a higher percentage of them registered to have depression, anxiety, and stress ranging from mild to highly severe [Table 2; Figure 3]. Price et al. have shown that both occasional poor sleepers as well as chronic poor sleepers report negative emotional states like being frequently exhausted, tensed, moody, irritable, and depressed.[24] However, these negative states were reported more by chronically poor sleepers.[24] Studies have shown a well-established link between inadequate sleep and mood impairment which elevates the risk for mental health illnesses such as depression, anxiety, and suicidal thoughts.[25]

Students of classes 10 and 12 of both schools showed more negative mood and had the least sleep duration and poorer sleep quality (especially for class 12) when compared grade-wise [Figures 1, 2, and 4–6]. Gupta et al., in their study on urban school-going adolescents, have revealed that students in higher grades had poorer sleep quality.[26] Increased academic demands in higher grades, especially for 10 and 12-class students may be the most likely cause. Singh et al. too have reported a higher level of depression as well as sleep deprivation among older adolescents.[6] A community-based study too has shown that older adolescents had lesser sleep duration compared to younger adolescents.[22] Apart from increased academic pressure, other causal association between reduced sleep duration and poorer sleep quality among students of higher grades still needs to be explored. Studies have explored several other factors like biological changes, use of technology (blue light emitted from smartphones/computers), social demands, and mental health issues (depression/anxiety) that can compromise sleep quality and quantity.[11]

Except for total sleep duration, which showed a negative correlation and was significant with depression, all three mood states (depression, anxiety, and stress) showed a significantly positive correlation with all other sleep parameters, namely sleep quality, daytime sleepiness, sleep latency, sleep disturbance, and daytime dysfunction scores. Fernandez-Mendoza et al., like the current study, found a substantial negative connection between sleep duration and depression.[27] In healthy teenagers, inadequate sleep has a considerable detrimental effect on a variety of emotional states.[28] While a significant bidirectional association was established between sleep duration and depression among adolescents.[8] Shin et al. concluded that with the physiological delay in sleep phase, adolescents were reported to suffer from excessive daytime sleepiness associated with its mental/physical manifestations and low grades.[5] Garbuio et al. observed a positive association between depression and sleep latency, stating higher depressive symptoms may have detrimental effects on sleep, primarily in terms of quality, latency, and drowsiness.[29] Sleep has a considerably [P = 0.001] higher impact on mood quality than mood has on sleep quality.[30]

Association of bedtime with sleep parameters

In comparison to students who went to bed early, those who stay up late have relatively poorer sleep quality, shorter sleep duration, and increased daytime sleepiness. Santos et al. too have identified adolescent’s delayed bedtimes to have a positive correlation with poor sleep quality and increased daytime sleepiness.[31]

Conclusion

Irrespective of the wake-up time on weekdays which are primarily governed by the school timings, students of the two-school slept nearly at the same time. However, students of school with early timings had lesser total sleep time, leading to higher sleep deprivation, greater sleepiness, depression, and poorer sleep quality. In addition to several key determinants affecting adolescents’ sleep habits, early school timing contributes to insufficient sleep within this population. Though changing or shifting the school timings has its own administrative limitations but educating the students and the parents about the importance of sleep, by sleep hygiene awareness programs is an alternative path to achieve the best. Thus, the exploration of sleep habits even by the primary care physician and their insistence on a regular and appropriate sleep schedule may play an important role in preventing sleep deprivation and its consequences among adolescents. Delayed bed timings and weekday/weekend irregularity are potentially modifiable variables and could be corrected by education and practice of sleep hygiene and its importance. Educating adolescents about the significance of sleep and evaluating the impact of providing non-pharmacological, behavioral interventions intended to improve the adolescent’s sleep quality and regularize their sleep patterns are recommended for future prospective studies.

Key points

• Irrespective of the school start time, the bedtime of the adolescents is almost the same.

• Adolescents in schools with early start time are more sleep deprived.

• Awareness regarding the importance of sleep duration and regularity of sleep schedules among adolescents is the need of the hour.

Key take-home message

Behavioral change in the sleep habits of adolescents is the need of the hour “Early to bed and early to rise makes a person healthy, wealthy and wise.”

Financial support and sponsorship

The Indian Council of Medical Research supported this work.

Conflicts of interest

There are no conflicts of interest.