The impact of daylight on suicide rates
利用挪威不同纬度地区日照时长的自然差异，基于45年全人口数据，发现日照时长增加对自杀率仅有微小且不显著的正向影响。
Since Durkheim and Morselli found a spring peak in suicides in the late 19th century, researchers have presented possible explanations, including daylight variation, for this seasonal pattern. Our identification strategy exploits the idiosyncratic variation in daylight within Norwegian regions, arising from the country's substantial latitudinal range. We use full population data for a period of 45 years in a pre-registered research design. We find a small and non-significant relationship: One extra hour of daylight increases the suicide rate by merely 0.75 % (95 % CI: -0.4 % to 1.9 %).