As your core cools for sleep, the blood vessels in your feet narrow, so feet feel icy first. That is normal, and socks genuinely help.
The NHS advises regular exercise and avoiding sudden temperature changes for cold-reactive hands and feet. The abnormal version has a signature: toes that turn white or blue then red in the cold, with pain, numbness, or pins and needles, which is Raynaud's, common but worth a GP mention, especially if new in adulthood. Around-the-clock cold feet with fatigue or breathlessness can signal iron deficiency anaemia, which is a blood test, not a sock upgrade.
What to do
Common questions
Why do I get cold feet in bed?
Feet get cold in bed because your body is doing sleep prep: as your core temperature drops toward sleep, blood vessels in your hands and feet narrow, which is normal and why extremities feel icy first. Cold bedroom air and bare floors make it obvious. For most people the answer is genuinely socks: warming the feet helps the vessel dilation that signals sleep readiness, which is why warm feet can help you fall asleep faster. Exercise helps circulation generally, and the NHS recommends regular exercise and avoiding sudden temperature changes for people whose fingers and toes react strongly to cold. The patterns that are not just cold feet: toes that change color in the cold, going white or blue then red, with pain, numbness, or pins and needles, which is the Raynaud's phenomenon the NHS describes, common and usually manageable but worth mentioning to a GP, especially if it starts in adulthood or comes with other symptoms. And feet that are cold around the clock, not just in bed, especially with constant fatigue, pale skin, or breathlessness, can ride along with iron deficiency anaemia, which the NHS lists among causes of feeling cold, so that pattern deserves a blood test rather than thicker socks.