title: Sleep-wake habits of schoolchildren according to grade.
abstract: Five hundred and twelve students aged from 6 to 18 years were administered the morningness-eveningness questionnaire and a sleep log. The mean morningness-eveningness score decreased with grade; this decrease was significant around the seventh grade. The habitual waking time showed no difference among grades but the habitual bedtime became later with grade; thus, the sleep length on weekdays decreased with grade. The percentage of students falling asleep during school lessons significantly increased from the eighth to 12th grade. We found that a delay of sleep phase, reduction of sleep length, increased daytime sleep, and transition to evening type occurred at around the seventh grade.
authors.affiliation: Graduate School, University of East Asia, Shimonoseki, Japan. harami@SHS.kyushu-u.ac.jp
authors.forename: H
authors.initials: H
authors.lastname: Shinkoda
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Y M
authors.initials: YM
authors.lastname: Park
authors.forename: H
authors.initials: H
authors.lastname: Nagashima
mesh_terms: D000293:Adolescent; D002648:Child; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D012016:Reference Values; D012892:Sleep Deprivation / Q000523:psychology; D012894:Sleep Stages; D013334:Students / Q000523:psychology*; D014851:Wakefulness