Suicides in the midnight sun—a study of seasonality in suicides in West Greenland

• Published in: Psychiatry research Vol. 133; no. 2; pp. 205 - 213
• Main Authors: Björkstén, Karin Sparring, Bjerregaard, Peter, Kripke, Daniel F.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 28.02.2005; Elsevier
• Subjects: Adolescent; Adult; Adult and adolescent clinical studies; Age Distribution; Aged; Aged, 80 and over; Aggression; Biological and medical sciences; Catchment Area (Health); Circadian Rhythm; Disruptive, Impulse Control, and Conduct Disorders - metabolism; Disruptive, Impulse Control, and Conduct Disorders - psychology; Female; Greenland - epidemiology; Human; Humans; Impulsiveness; Incidence; Light; Male; Medical sciences; Medicin och hälsovetenskap; Middle Aged; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Seasons; Serotonin; Serotonin - metabolism; Sex Distribution; Suicide; Suicide - statistics & numerical data; North America; Greenland; America; Human; Serotonin; Aggression; Impulsiveness; Light; Impulsivity; Seasonal variation; Neurotransmitter; Suicide
• ISSN: 0165-1781; 1872-7123
• DOI: 10.1016/j.psychres.2004.12.002

Greenland is the most extreme of human habitats in regard to annual changes in natural light. From being very low, the rate of suicides in Greenland has increased during the past few decades to be among the highest in the world. Several studies have shown seasonality in suicides with spring or summer peaks, but this has not been previously shown in Greenland. Official data from 1968 to 1995 from West Greenland were pooled. A significant seasonality in the 833 suicides was found using Rayleigh's test, a peak in June and a trough in the winter. Suicides increased during the period, and reached high rates in most age groups, up to 577 per 100,000 person-years in men aged 15–24 years in 1990, and up to 147 per 100,000 person-years in women aged 15–24 years in 1995. Violent methods of suicide were used by 93%. Depression has been reported uncommonly. High alcohol intake and extended periods of light in the summer may contribute to impulsive–aggressive summer suicides.