A consistent sleep and wake window
A fixed sleep window beats anything you could buy in a bottle.
Strong consensus“Regularity beats duration in most of the data we have. The body loves to know what time it is.”
A cool bedroom, around 18 degrees
A cool room near 18 degrees deepens the slow-wave sleep that repairs you.
RecommendedFor deeper slow-wave sleep.
The strongest voice
“Core temperature has to fall for sleep to begin. A cool room simply removes the obstacle.”
In their own words
One faithful sentence per source, linked to the moment it was said; quiet chips mark where money is involved.
a sleep medicine doctor recommend
“Somewhere between 16 and 19 degrees suits most people; the body does its best thermoregulation under a duvet in cool air.”
a sleep medicine doctor · source video · 00:09:12
a physiologist PhD recommend
“The distal skin warming that precedes sleep onset works best against a cool background.”
a physiologist PhD · podcast episode · 00:44:30
a GP conditional
“Older adults and those with thyroid issues may genuinely need it warmer; comfort still counts.”
a GP · interview · 00:21:55
Worth discussing with your GP, especially if you take medication or are pregnant. Entrain describes what is publicly taught; it does not prescribe.
More from sleep
Nightly melatonin as a default
Our sources are genuinely split: an occasional tool, or a hormone best left alone.
Genuinely contested“Melatonin is a timing signal, not a sedative. Used as a nightly sledgehammer it often disappoints, and retail doses are far above what the pineal ever makes.”
Mouth taping at night
An early signal worth watching, once snoring and apnoea are ruled out.
An early signal“Nasal breathing at night is clearly worth encouraging. Whether tape is the right way to get there is a much smaller question than the internet suggests.”