Socks in bed
Short answer: Warm feet help the body fall asleep faster. The sock has to be thin and without tight elastic, or it works against the purpose.
Why it works
The body lowers its core temperature before sleep by sending heat out to the hands and feet. If the feet are cold, the blood vessels cannot widen and the process goes more slowly. Warm feet speed it up.
The sock that suits
Thin, soft and with a wide cuff that does not squeeze. A thick sock makes the foot damp, and a damp foot goes cold during the night. See bamboo socks for women.
The alternative
A hot water bottle at your feet for ten minutes before you lie down works the same way with nothing to sleep in. See bamboo socks for men and bamboo nightwear for women.
Frequently asked questions
Is it unhealthy to sleep in socks
No, if they are clean and do not squeeze.
Should they be thick
No. Thin socks keep the foot warm without making it damp.
What if you get too warm
Then you kick them off in your sleep, and that is perfectly fine.