Sleep Duration Associated with the Lowest Risk of Depression/Anxiety in Adolescents.
To investigate sleep duration associated with the least depression/anxiety in adolescence.



Grades 7-12 Japanese students (n = 18,250, aged 12-18 y) from public junior high/high schools were studied in a cross-sectional design. Due to missing/implausible data, 15,637 out of the 18,250 students were statistically analyzed. Relationship between sleep duration on school nights and depression/anxiety, measured using self-report questionnaires, including the General Health Questionnaire-12 (GHQ-12), were studied by sex and grade, controlling for bedtime regularity.



When sleep duration was classified by 1-h intervals, rate of adolescents with a GHQ-12 score ≥ 4 was the lowest in males and females who slept 8.5-9.5 h and 7.5-8.5 h, respectively, (designated "references") in both grades 7-9 and 10-12. The rate was significantly higher than the references in both males and females who slept < 7.5 h, regardless of grade (P < 0.05, logistic regression). GHQ-12 tended to be worse in adolescents (2.0%-13.5%) who slept longer than the references. Sleep duration for the minimum GHQ-12 score was estimated to be 8.8 and 8.5 h in males, and 8.0 and 7.5 h in females, in grades 7-9 and 10-12, respectively, using the General Additive Model.



Sleep duration of ≥ 8.5 h on school nights may be associated with the lowest risk of depression/anxiety on average in male adolescents. Although the duration was estimated to be shorter in females (≥ 7.5 h) than males, this should be interpreted carefully. Most adolescents may currently be sleeping less than the optimal duration.



A commentary on this article appears in this issue on page 1491.
Department of Physical and Health Education, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Yasutaka
Y
Ojio
Department of Psychiatry and Behavioral Science, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan.
Atsushi
A
Nishida
Department of Neuropsychiatry, Kochi University School of Medicine, Kochi, Japan.
Shinji
S
Shimodera
Department of Physical and Health Education, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Fumiharu
F
Togo
Department of Physical and Health Education, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Tsukasa
T
Sasaki
D000293:Adolescent; D001007:Anxiety / Q000453:epidemiology*; D002648:Child; D003430:Cross-Sectional Studies; D003863:Depression / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D012307:Risk Factors; D012574:Schools; D057566:Self Report; D012890:Sleep / Q000502:physiology*; D013334:Students / Q000523:psychology; D011795:Surveys and Questionnaires; D013997:Time Factors
General Health Questionnaire-12; adolescents; age; mental health; sex; sleep duration