An epidemiological study on gender differences in self-reported seasonal changes in mood and behaviour in a general population of northern Sweden.

Gender differences have been reported regarding symptoms, prevalence and heritability of seasonal affective disorders (SAD). We focus on gender aspects in this study of self-reported seasonal changes in mood and behaviour in a general population. The Seasonal Pattern Assessment Questionnaire (SPAQ) was completed by 2620 adults (55.6% women) aged 35-85 years, enrolled in the Betula prospective random cohort study of Umeå, Sweden. October to February turned out to be suitable winter months. SAD was found in 2.2% and sub-syndromal SAD (S-SAD) in 5.7%. Women had about 1.5 times higher prevalences than men, and seasonality problems decreased with age in both genders. Preference for eating least was distributed with a peak in summer, whereas preference for eating most had a major peak in winter (winter eaters) and a minor peak in summer (summer eaters). Significantly more of winter eaters in women, and significantly more of summer eaters in men, felt worst in winter. Seasonal change in weight was considered significantly as a problem by women but not by men. Winter behaviour of sleeping most was considered significantly as a problem by men but not by women. Women reacted significantly to temperature-related changes (negatively to cold/short days and positively to hot/long days), whereas men reacted significantly to sunshine-related changes (negatively to cloudy days and positively to sunny days). Subtle gender differences may thus underlie the pathophysiology of seasonal problems. Studies of an eventual efficacy of treating SAD women with raised ambient temperature, and gender-specific comparisons with other therapies, would be of interest.