Psoriasis and seasonal variation: A systematic review on reports from Northern and Central Europe—Little overall variation but distinctive subsets with improvement in summer or wintertime

Positive influence of the sun on psoriasis is a common assumption in dermatology. Other season-related factors such as mental health may interfere. However, the role of seasonal effects on psoriasis needs to be clarified. This review aims to systematically analyze the literature on seasonal variation on psoriasis with emphasis on Northern and Central Europe representing temperate climate conditions.Enrolled literature was identified through...