Mental distress during winter. An epidemiologic study of 7759 adults north of Arctic Circle.

The prevalence of mental distress in a general population north of the Arctic Circle at 69 degrees N was studied over 4 midwinter months. Within the framework of a health survey for coronary heart disease, 3 questions about depression, coping problems and insomnia were posed. They were answered by 7759 people randomly assigned to a survey date from November to February. The extreme lack of daylight in December and January taken into consideration, the prevalence of mental distress found, 14% in men and 19% in women, is remarkably low compared with previous epidemiologic research. Except for insomnia in women, which was most prevalent in December, no significant relationship between month of survey and any of the 3 symptoms were found. Thus, the findings cast some doubt upon the importance of daylight for mental distress in the general population.