Summary
Deliberate cold exposure has positive biological effects on brain biology, metabolism, and brown fat stores. It can be healthy for sperm by reducing heat and helping with lowered sperm count and overall reduced sperm quality. In females, deliberate cold exposure can regulate cortisol, hormone production, and fertility. However, the benefits of cold exposure on hormone levels are indirect, achieved by reducing stress and cortisol levels. Deliberate cold exposure should be done gradually and at an uncomfortably cold but safe temperature.