Sleep and temperature.
 

https://www.zmescience.com/science/t...cadian-rhythm/ Shafer adds that the circadian system creates a daily rhythm in temperature which is an important cue for when nap time comes around. So, while you may think our bodies run at a steady 37°C (98.6°F), “in fact, it’s fluctuating.” As the clock ticks nearer to wakefulness, our circadian system warms the body up. When it’s close to bedtime, it lowers our internal temperature. This effect is independent of the temperature of the room you’re sleeping in.

The paper “Circadian clock neurons constantly monitor environmental temperature to set sleep timing” has been published in the journal Nature.

Cold rooms and weather make people sleepy and fatigued?

Any thoughts on why women like the room much warmer than men when going to bed?

"Hydration

Puberty also stimulates the appearance of facial hair in men and gives rise to sweat secretions. Males have more Lactic Acid in their sweat, which accounts for a lower pH (.05 lower) when compared to female sweat. Men also sweat more than twice as much as women and are more prone to sweating, which is stimulated by an increase in body temperature. However, male skin appears to be better hydrated than women’s, which is fortunate, as men are less likely to apply a hydrating moisturizer to their body or face. Perhaps the excess sweating and production of Lactic Acid, a known natural humectant for the skin, is responsible for the level of tissue hydration."

Ref: Dermal Institute