Impact of sleep problems on daytime function in school life: a cross-sectional study involving Japanese university students

Abstract

Background: The aims of this study were 1) to clarify the prevalence of sleep problems (insomnia, insufficient sleep, and delayed sleep-wake phase) among Japanese university students; 2) to examine sociodemographic characteristics, lifestyle, and sleep-related symptoms in each sleep problem; and 3) to evaluate the association between the above-mentioned sleep problems and daytime dysfunction in school life.

Methods: Self-report questionnaire surveys were conducted at eight universities in Japan, and we received 1034 valid answers (78% female). The questionnaire consisted of socio-demographic characteristics, information on lifestyle, sleep pattern, sleep-related symptoms, and daytime dysfunction in school life. Groups with insomnia, behaviorally induced insufficient sleep syndrome (BIISS), delayed sleep-wake phase (DSWP), and BIISS + DSWP were defined. To identify the association between sleep problems and daytime dysfunction in school life, the generalized linear mixed effect model was conducted.

Results: Sleep duration on weekdays was 5.9 ± 1.2 h, and 38.2% of the students had a sleep duration < 6.0 h. About 16% of the students were categorized as evening-type individuals. More than half of the students (56.1%) had excessive daytime sleepiness. Insomnia was associated with tardiness (aOR: 0.8, 95%CI: 0.7-0.9) and falling asleep during class (aOR: 1.6: 95%CI: 1.4-2.0). BIISS was associated with tardiness (aOR: 1.5, 95%CI: 1.1-2.2) and interference with academic achievement (aOR: 1.9, 95%CI: 1.3-2.6). DSWP and BIISS + DSWP were associated with absence (aOR: 3.4, 95%CI: 2.2-5.1 / aOR: 4.2, 95%CI: 3.2-5.6), tardiness (aOR: 2.7, 95%CI: 1.8-4.1 / aOR: 2.2, 95%CI: 1.6-2.8), falling asleep during class (aOR: 2.6, 95%CI: 1.4-4.8 / aOR: 7.6, 95%CI: 3.3-17.2), and interference with academic achievement (aOR: 2.6, 95%CI: 1.7-3.9 / aOR: 2.1, 95%CI: 1.6-2.8).

Conclusions: Students with DSWP and BIISS + DSWP were significantly associated with daytime dysfunction in school life, i.e. absence, tardiness, falling asleep during class and interference with academic achievement. Students displaying BIISS + DSWP were considered to have a relatively more serious condition compared with those with only insomnia, DSWP, or BIISS. It is therefore of utmost importance that university students aim to prevent DSWP and BIISS which were associated with daytime function in school life.

Keywords: Attendance; Behaviorally induced insufficient sleep syndrome; Daytime dysfunction; Delayed sleep-wake phase; Insomnia; Tardiness.

Fig. 1

Definition of the BIISS, DSWP, and BIISS + DSWP groups. BIISS, behaviorally induced insufficient sleep syndrome; DSWP, delayed sleep-wake phase

Fig. 2

Prevalence of sleep problems and sleep-related symptoms. BIISS, behaviorally induced insufficient sleep syndrome: sleep duration on weekdays < 6 h, difference in sleep duration on weekdays and weekends ≥2 h, and Epworth Sleepiness Scale score ≥ 11. DSWP, delayed sleep-wake phase: bedtime before 1:00 am on weekdays and Morningness-Eveningness Questionnaire score < 42. Insomnia: Athens Insomnia Scale score ≥ 6 and one or more of “Difficulty initiating sleep,” “Difficulty maintaining sleep,” and “Early morning awakening”. REM parasomnia: nightmares and/or acting out dreams. NREM parasomnia: night terrors, defective awakening, and/or sleep walking