An Umbrella Systematic Review of Seasonality in Mood Disorders and Suicide Risk: The Impact on Demand for Primary Behavioral Health Care and Acute Psychiatric Services.

To review the current literature focusing on the most recent systematic reviews relating to mood, suicide, and psychiatric service utilization. A systematic literature search of PubMed, CINAHL, and PsycINFO databases using the search terms "Systematic review" AND "season*" AND mood OR depression OR bipolar OR psychosis OR suicid* OR psychiatr* initially yielded 209 results. After screening by title and abstract for relevance, 6 records remained, while a further 3 were identified after screening of reference lists. A qualitative synthesis of these results was then performed due to data heterogeneity between studies. We found evidence of winter peaks for depressive symptoms and suggestions of summer peaks for suicidal activity, emergency department (ED) self-harm presentations, and manic-related hospital admissions. Suicide is 11%-23% more frequent in spring and summer. ED suicide attempts are also 1.2-1.7 times higher in spring and summer compared to winter. Admissions for mania are 7.4%-16% higher in spring and summer, while there are 1.5 times more admissions for bipolar depression in winter months. There is a summer peak for many aspects of mental health activity, particularly in terms of acute hospital utilization and suicidality. This is contrary to the winter-related peak of depressive symptoms. Further research is needed to affirm these findings.