A study in Brazil found that delaying the start to the school day by an hour improved sleepiness and mood profile in children attending high school.
According to the Perfect Storm Model, early school start time is the primary factor that is prompting adolescents to an early wake-up time. Insufficient sleep in adolescents has been pinpointed as a public health concern, as circadian regulation of sleep goes through significant changes during adolescence. The present study aimed to evaluate the effect of a 1-hour delay of the start of school on sleep, sleepiness, and cognition in high school students.
The study took place in a private high school in Palotina, Brazil. At least 50% of students from each school level were invited to take part in the study in order to achieve a representative sample. The within-subject study had 3 weeks of evaluation. In the first (week A) and last (week C) weeks, school started at the regular time of 7:30 AM and in the second week (week B), the school start time was delayed by 1 hour.
All participants completed a baseline questionnaire with sociodemographic information, the Munich Chronotype Questionnaire, health status, and they received an actigraph with instructions on how to use it. All participants wore the actigraph during all 3 experimental weeks.
All participants performed the Karolinska Sleepiness Scale (KSS) when they arrived at school and before they left school. They also performed a set of evaluations that included an adapted version of the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), and a mood profile with the Profile of Mood States (POMS) and the Hospital Anxiety and Depression Scale (HADS). These evaluations were taken once a week.
A total of 38 students were included in the study after the evaluation period. Data from 21 participants was received for the actigraphy. The researchers found that there was no significant change on bedtime in the different weeks. The mean (SD) time that adolescents went to bed was 23:18 (00:42) in week A, 23:29 (00:36) in week B, and 23:28 (00:41) in week C.
Adolescents woke up later in week B, with no effect of sex. Participants woke up at 6:54 (00:12) in week A, 7:42 (00:30) in week B, and 6:46 (00:15) in week C. Adolescents spent a longer duration of time in bed in week B. Adolescents spent 07:33 (0:38) hours in bed in week A, 08:13 (0:43) hours in bed in week B, and 7:16 (0:47) hours in bed in week C. There was also an extension of sleep duration in week B (07:35 [0:48]) compared with week A (07:03 [0:41]) and week C (06:46 [0:48]). Female adolescents had longer total sleep duration compared with male adolescents in a linear mixed-model analysis.
Starting school later was also effective in reducing daytime sleepiness using the ESS. Participants had lower ESS scores in week B (8.26 [4.26]) compared with week A (10.10 [3.24]) and week C (9.63 [3.62]). Using the KSS, adolescents were found to have a lower mean KSS score in week B compared with week A and week C.
A significant reduction in the scores for depression in the HADS was found in week B (4.82 [0.54]) compared with week A (5.89 [0.53]) but there was no significant change between week B and C (5.49 [0.54]). This was also found in the depression domain of POMS. Adolescents reported feeling less fatigue and tension in week B compared with weeks A and C. Adolescents also reported lower scores in the anger-hostility domain in week B compared with weeks A and C.
There were some limitations to this study. The sample size for the study was small. The school day was also shortened by 35 minutes during week B, which may have affected the results. Repetition of measures could have also been another limitation, as learning could mask effects of sleep on the mood profile.
The researchers concluded that the study proved that a delay in school start time was beneficial to adolescents’ sleep duration, sleepiness, and mood profile.
De Araujo LBG, Bianchin S, Pedrazzoli M, Louzada FM, Beijamini F. Multiple positive outcomes of a later school starting time for adolescents. Sleep Health. 2022;8(5):451-457. doi:10.1016/j.sleh.2022.04.002