Annual fluctuations of sunlight and suicides in a region South of the Tropic of Cancer

Abstract

Studies in temperate countries show a direct correlation between the hours of daily light and the frequency of suicides. This relationship is damped in countries at the equatorial level, and what happens near the tropic lines is unknown. In this paper the suicide rates as well as the monthly average of daily light were analyzed in hours from 1990 to 2016 in Campeche, Mexico, a place with a high rate of suicide deaths and near the latitude of the Tropic of Cancer. The results showed that total suicides and sunshine were positively correlated (r = 0.649; p = 0.022) and the peak of maximum light in June coincides with the maximum suicide peak. There were non-significant peaks of higher suicides in June and December for men and in May for women. However, a clear, significant peak (p = 0.003) showed up in spring. We recommend strengthening the prevention programs during these periods.

Keywords:

• Suicide
• sunlight
• seasonality
• latitude

Acknowledgments

The authors are grateful for the support provided by Dr. José Franco for the realization of this work.