ArticleClinical epidemiology2022
Seasonal Effects on Hospitalizations Due to Mood and Psychotic Disorders: A Nationwide 31-Year Register Study.
Article in Clinical epidemiology, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 8 papers.
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Who cites it
8 citing papers in PubMed.
- Primary Care Prescribing Patterns for Benzodiazepines and Z-Drugs, and Evidence Gaps Concerning Hydroxyzine and Seasonality: A Systematic Review.Clinics and practice · 2026Review
- Seasonal patterns of long sickness absence due to 411 diagnostic groups: a nationwide register-based study in Finland during 2020-2023.Scandinavian journal of public health · 2026Article
- Sunshine duration and episodes of mental disorders and the inverse effect modification by ambient temperature.BMC medicine · 2026Article
- Seasonal metabolic oscillation: adiposity cycling as a candidate amplifier of mood seasonality in seasonal affective and bipolar disorders.Frontiers in psychiatry · 2026Article
- Will things feel better in the morning? A time-of-day analysis of mental health and wellbeing from nearly 1 million observations.BMJ mental health · 2025Article
- Association between a large change between the minimum and maximum monthly values of solar insolation and a history of suicide attempts in bipolar I disorder.International journal of bipolar disorders · 2024Article
- Higher Seasonal Variation of Systemic Inflammation in Bipolar Disorder.International journal of molecular sciences · 2024Article
- Seasonal patterns of sickness absence due to diagnosed mental disorders: a nationwide 12-year register linkage study.Epidemiology and psychiatric sciences · 2023Article
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Authors and funding
7 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Purpose: To examine seasonal patterns of hospital admissions due to mood and psychotic disorders and to investigate whether the admission rates show variation according to the seasonal daylength (photoperiods). Patients and Methods: A retrospective nationwide register-based cohort of all psychiatric admissions (N=978,079) during 1987-2017 in Finland was utilized. The smoothed time-series of adjusted ratio of observed and expected (O/E) daily counts were estimated to examine seasonal variation. The mean O/E with 95% confidence intervals (CI) was used to study the admission rates by photoperiods. The calendar days were classified into the 71-day photoperiods based on the daylength (long/summer, short/winter, equal/spring, equal/fall) and the pace of change in daylength (slowly/rapidly increasing/decreasing daylength). Results: Manic episodes peaked in summer during the long (mean O/E=1.10, 95% CI=1.06-1.13) and slowly decreasing (1.09, 1.06-1.13) photoperiods and had a nadir in winter during the slowly increasing (0.93, 0.89-0.98) photoperiod. Admissions for unipolar depressive (UPD) episodes peaked in autumn and in spring at the end of the rapidly decreasing (1.03, 1.02-1.04) and increasing (1.03, 1.01-1.04) photoperiod, and dropped in summer during the long and slowly decreasing (0.95, 0.94-0.96) photoperiods. Bipolar depressive (BPD) and mixed episodes signaled excess admissions in autumn and in spring. Admissions for schizophrenia were higher than expected from summer to early-autumn, during the long and slowly decreasing photoperiods (1.02, 1.02-1.03), and lower than expected in other seasons, especially in mid-spring during the rapidly increasing photoperiod (0.98, 0.98-0.99). Conclusion: The study indicates the seasonality and photoperiodicity of mental disorders, especially for manic episodes. The seasonal pattern is similar between schizophrenia and manic episodes, and between UPD, BPD, and mixed episodes.
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