[Retric]

> because body temperature rises during sleep

You have that backwards. “People maintain a fairly consistent body temperature during the day which drops at night by around 1.8 degrees Fahrenheit. However, some people still feel hot at night due to their unique body composition, sleep environment, something they ate or drank, or other medical reasons.” https://www.sleepfoundation.org/sleep-faqs/why-do-i-get-so-h....

Deeper look: “Core body temperature (CBT) reductions occur before and during the sleep period, with the extent of presleep reductions corresponding to sleep onset and quality.” https://journals.physiology.org/doi/abs/10.1152/japplphysiol...

Critically your body intentionally lowers temperature including changes to skin capillaries and sweating, it’s not simply lowering temperature from not moving. So you can wake up sweating even if things where fine when you went to sleep.

[derefr]

Maybe technically true as a matter of biology in isolation, but mostly not in practice — specifically due to that "something they ate or drank" part. The basal body temperature reduction that happens at night really isn't relevant for anyone who consumes any amount of caffeine during the day (which is most people), as when caffeinated, the BBT shift downward at night isn't accompanied by a complementary upward shift in comfortable/tolerable air temperature. Rather the opposite.

Caffeine, as a cholinergic, constricts peripheral blood vessels, and reduces bloodflow; and as a diuretic, it also reduces interstitial-fluid retention in peripheral tissues. These effects combine to decrease your skin temperature (or rather, to make your skin temperature less reflective of your core temperature and more reflective of the ambient air temperature); while very slightly increasing your core temperature (and blood pressure! Which is one reason caffeine is bad for your heart!)

Most of your heat-sensing nerves are in your periphery, not in your core. So caffeine, by making your skin cooler, makes you feel cooler (even though your basal body temperature goes up!) to which your body responds by sweating less (even though caffeine, as a cholinergic, would force you to sweat in great-enough amounts. See: SLUDGE syndrome.)

Most people don't drink caffeine after a certain time in the evening; and so at night, whatever caffeine was in their bodies has a chance to flush out — which then suddenly allows bloodflow, blood pressure, and interstitial fluid to wash back out to their skin and extremities — and with that comes an increase in skin temperature, "hot" qualia, and triggered sweating from signalled overheating (i.e. the same reason you sweat from spicy food even though your BBT isn't increasing.)

[distances]

I definitely heat up in the evening when laying down. I may need socks + woollen socks through the day, but it's socks off time during the evening movie. And sleeping time means full-body heating, which my partner really appreciates.

With my partner we have complementary heating systems. I get warm in the evening when they are cold, and they warm up after eating which does nothing for me. The difference is radical.

I guess partly due to this I would never spend a day without a shower in the morning. I've never been sick enough to skip a morning shower, even in a high fever (or especially then I guess, due to sweating more than usual). The dirty feeling is just too much to bear.

[Retric]

You feel the sensation of warmth because your body is trying to cool down. It does so by raising the temperature of your skin so more heat is dumped into the environment. This is part of the reason why drinking can lead to hypothermia. https://pubmed.ncbi.nlm.nih.gov/1811578/ “Alcohol is a dominant cause of death in urban hypothermia. Drinking alcohol gives a pleasant feeling of warmth.”

Try taking your core body temperature using a thermometer rather than relying on perceived temperature.

[distances]

Sounds logical. I don't mind which mechanism is behind it, but the ability to heat up any sleeping spot to a comfortable temperature for two is feature I quite like.

[thisislife2]

Yeah, body temperature falls when you sleep. In fact, that's one of the tips give to insomniacs to help them sleep - have a bath at night, preferably with cold water.