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dc.contributor.authorØverland, Simon Nygaard
dc.contributor.authorWoicik, Wojtek
dc.contributor.authorSikora, Lindsey
dc.contributor.authorWhittaker, Kristoffer
dc.contributor.authorHeli, Hans
dc.contributor.authorSkjelkvåle, Fritjof Stein
dc.contributor.authorSivertsen, Børge
dc.contributor.authorColman, Ian
dc.identifier.citationEpidemiology and Psychiatric Sciences. 2019, 29 (e31), .nb_NO
dc.description.abstractAims Lay opinions and published papers alike suggest mood varies with the seasons, commonly framed as higher rates of depression mood in winter. Memory and confirmation bias may have influenced previous studies. We therefore systematically searched for and reviewed studies on the topic, but excluded study designs where explicit referrals to seasonality were included in questions, interviews or data collection. Methods Systematic literature search in Cochrane database, DARE, Medline, Embase, PsychINFO and CINAHL, reporting according to the PRISMA framework, and study quality assessment using the Newcastle-Ottawa scale. Two authors independently assessed each study for inclusion and quality assessment. Due to large heterogeneity, we used a descriptive review of the studies. Results Among the 41 included studies, there was great heterogeneity in regards to included symptoms and disorder definitions, operationalisation and measurement. We also observed important heterogeneity in how definitions of ‘seasons’ as well as study design, reporting and quality. This heterogeneity precluded meta-analysis and publication bias analysis. Thirteen of the studies suggested more depression in winter. The remaining studies suggested no seasonal pattern, seasonality outside winter, or inconclusive results. Conclusions The results of this review suggest that the research field of seasonal variations in mood disorders is fragmented, and important questions remain unanswered. There is some support for seasonal variation in clinical depression, but our results contest a general population shift towards lower mood and more sub-threshold symptoms at regular intervals throughout the year. We suggest future research on this issue should be aware of potential bias by design and take into account other biological and behavioural seasonal changes that may nullify or exacerbate any impact on mood.nb_NO
dc.publisherCambridge University Pressnb_NO
dc.rightsNavngivelse 4.0 Internasjonal*
dc.titleSeasonality and symptoms of depression: A systematic review of the literaturenb_NO
dc.typeJournal articlenb_NO
dc.typePeer reviewednb_NO
dc.source.journalEpidemiology and Psychiatric Sciencesnb_NO
dc.description.localcodeCOPYRIGHT: © The Author(s) 2019 This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (, which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.nb_NO
cristin.unitnameInstitutt for psykisk helse

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Navngivelse 4.0 Internasjonal
Except where otherwise noted, this item's license is described as Navngivelse 4.0 Internasjonal