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Sleep characteristics, chronotype and winter depression in 10–20‐year‐olds in northern European Russia
Author(s) -
Borisenkov Mikhail F.,
Petrova Natalia B.,
Timonin Vladimir D.,
Fradkova Lyudmila I.,
Kolomeichuk Sergey N.,
Kosova Anna L.,
Kasyanova Olga N.
Publication year - 2015
Publication title -
journal of sleep research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 117
eISSN - 1365-2869
pISSN - 0962-1105
DOI - 10.1111/jsr.12266
Subject(s) - chronotype , demography , depression (economics) , psychology , insomnia , population , sleep debt , sleep (system call) , sleep onset , odds ratio , medicine , circadian rhythm , psychiatry , sleep disorder , sociology , economics , neuroscience , computer science , macroeconomics , operating system
Summary The purpose of this work was to examine the relationships between geographical coordinates and the prevalence of winter depression ( SAD W ), and to compare the sleep characteristics and chronotype of youths with and without SAD W . We conducted a cross‐sectional study of self‐reported sleep characteristics, chronotype and winter depression in northern European Russia. Two questionnaires, the Munich Chronotype Questionnaire ( MCTQ ) and the Seasonal Pattern Assessment Questionnaire ( SPAQ ), were administered to a total of 3435 adolescents aged 10–20 years (1517 males and 1918 females). The prevalence of SAD W in the study population was 8.4% and sub‐ SAD W 11.8%. Four variables predicted the likelihood of SAD W in youths: sex [higher in females: odds ratio ( OR ): 1.87, P < 0.0001], age (increases with age: OR : 1.09, P < 0.001), latitude (higher in the North: OR : 1.49, P < 0.029) and position in the time zone (higher in the West: OR : 1.61, P < 0.001). Later sleeping and waking, longer sleep latencies, more severe sleep inertia, shorter total sleep times and lower sleep efficiencies were observed in both males and females with SAD W . The influence of SAD W on sleep characteristics was more pronounced on school days. Significant phase delays of the sleep–wake rhythm and severe social jetlag (the difference between the mid‐point of sleep phase at weekends and on workdays) were observed in females with SAD W , but not in males. There are significant differences in sleep characteristics and chronotype between people with SAD W and no‐ SAD . We demonstrate that both latitude of residence and location within the time zone are significant predictors of SAD W in young inhabitants of the North.