title: High prevalence of self-reported depressive mood during the winter season among Swedish senior high school students.
abstract: OBJECTIVE
  There are few studies regarding the prevalence of seasonal variation in mood among children and adolescents. The main objective of this study was to estimate the prevalence of self-reported depressive mood during the winter season among Swedish adolescents and to investigate gender differences. Another aim was to analyze the factor structure and internal consistency of the Kiddie SPAQ (K-SPAQ), a pediatric version of the Seasonal Pattern Questionnaire (SPAQ).
  
  
  METHODS
  All students 17 to 18 years old, registered in the second year of senior high school in Falun, a district in central Sweden, were screened with the K-SPAQ in January 2003 (response rate 87.3%, n = 756).
  
  
  RESULTS
  The prevalence of self-reported depressive mood during the winter season was estimated at 20.1% (n = 151/751) and was higher among girls (25.5%) than boys (13.8%). Approximately 8% reported more severe depressive symptoms. Depressive mood during the summer was rare (0.1%, n = 1/751). Factor analysis of the General Seasonal Score items in the K-SPAQ revealed a two-factor structure. A Cronbach's alpha of 0.87 demonstrated a good internal consistency.
  
  
  CONCLUSIONS
  Depressive symptoms during autumn and winter were common among Swedish senior high school students, especially among girls. This is probably an underdiagnosed condition among adolescents that ought to receive more attention from the health and school authorities.
authors.affiliation: From the Center for Clinical Research Dalarna (CKF) and the Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden (C.R.); the Sleep Disorders Center, Department of Internal Medicine, Avesta Hospital, Avesta, Sweden, and CKF (J.U.); and the Department of Public Health and Caring Sciences, Uppsala University, and CKF (P.O.S.). Electronic address: cecilia.rastad@ltdalarna.se.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Rastad
authors.affiliation: From the Center for Clinical Research Dalarna (CKF) and the Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden (C.R.); the Sleep Disorders Center, Department of Internal Medicine, Avesta Hospital, Avesta, Sweden, and CKF (J.U.); and the Department of Public Health and Caring Sciences, Uppsala University, and CKF (P.O.S.).
authors.forename: Jan
authors.initials: J
authors.lastname: Ulfberg
authors.affiliation: From the Center for Clinical Research Dalarna (CKF) and the Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden (C.R.); the Sleep Disorders Center, Department of Internal Medicine, Avesta Hospital, Avesta, Sweden, and CKF (J.U.); and the Department of Public Health and Caring Sciences, Uppsala University, and CKF (P.O.S.).
authors.forename: Per-Olow
authors.initials: PO
authors.lastname: Sjödén
mesh_terms: D000293:Adolescent; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D011581:Psychological Tests; D011594:Psychometrics; D015203:Reproducibility of Results; D016574:Seasonal Affective Disorder / Q000453:epidemiology* / Q000503:physiopathology / Q000523:psychology; D017678:Sex Distribution; D013548:Sweden / Q000453:epidemiology