Six Young Men, Two Nights: How Good Is the Bed Socks Sleep Evidence?

The advice comes around every fall. Wear socks to bed and you'll fall asleep faster. It usually arrives attached to a study, which is more than most sleep tips can offer, and that study was published in a peer-reviewed journal in 2018. It also had six people in it, all of them men in their early twenties.

Photo: Livi Po / Unsplash

What the study did

Researchers at Seoul National University had six young men sleep through two sessions each, once wearing bed socks and once without, in random order, in a room held at 23°C (about 73°F). Wrist actigraphy tracked seven hours of sleep each time. The researchers also monitored heart rate, rectal temperature, and skin temperature at several sites throughout.

With socks on, the men fell asleep 7.5 minutes faster on average, slept 32 minutes longer, woke 7.5 fewer times across the night, and had sleep efficiency 7.6 percentage points higher. Their foot temperature ran 1.3°C warmer, and the difference between foot temperature and trunk temperature grew larger. That difference is the physiological signal the researchers were looking for. Core temperature didn't change.

There was one more result, and it complicates the others. When the men filled out a sleep questionnaire the next morning, their own ratings showed no difference between the two nights, which means the devices recorded a change that the men themselves didn't notice.

Why warm feet can help you fall asleep

The physiology behind this has been understood for decades. Blood vessels in the hands and feet dilate before sleep, heat leaves the body through them, core temperature falls, and sleep follows. The difference between the skin temperature of your feet and the skin temperature of your trunk predicts how quickly you'll fall asleep, and it predicts that better than core temperature does.

Researchers have tested many times whether warming the skin on purpose starts that same process. A meta-analysis pooling 13 studies with usable data found that a warm bath or shower at 40 to 42.5°C, taken one to two hours before bed, shortened the time to fall asleep and improved self-rated sleep quality. As little as 10 minutes in the water was enough to produce the effect.

Warming only the feet has produced weaker results. A 2025 meta-analysis pooled six randomized trials of hot foot baths covering 176 patients. The improvements it found didn't reach statistical significance, and the authors rated the underlying studies as low quality with a high risk of bias.

Age changes the results as well. A study that compared footbaths and heatable bed socks across age groups found sleep onset sped up in adults, the effect weakened in older adults, and in older adults who already had insomnia, none of the treatments sped up sleep onset at all. The people most likely to go looking for help with sleep are the same group in whom warming the feet has worked least well.

What cold feet at bedtime can tell you

Cold feet at bedtime is information, and my instinct is to treat it as a question before I treat it as a problem to cover with wool. If your feet are reliably cold in a warm room, I want to know what the thyroid is doing, what your ferritin level is, and how the circulation to your hands and feet behaves during the day rather than only at night. Socks warm the foot, and they do nothing about why the foot went cold in the first place.

That question comes up constantly in the patients I see for mast cell activation and dysautonomia. A lot of those patients have trouble controlling blood flow to their hands and feet, which shows up as things like cold hands and feet, blood pooling in the legs on standing, or a body temperature that swings for no obvious reason. Falling asleep is often hard for them because of it. Letting heat out before sleep depends on the blood vessels in the hands and feet widening, and in these patients those vessels often don't widen when they should. A sock works around that problem, which is fine, though it does nothing to change how those blood vessels respond.

The reference I keep coming back to for the wider question is an umbrella review of complementary and alternative insomnia treatments. The authors are blunt in their summary: cognitive behavioral therapy for insomnia is the recommended first-line treatment and is nowhere near widely enough available, and the alternatives that have been studied mostly improve how people rate their own sleep rather than what instruments record. The bed sock study shows the reverse, with the instrument measurements improving while the men's own ratings stayed the same. Whichever way the mismatch goes, a result from a study this small shouldn't carry much weight.

Should you try bed socks?

1. Try the socks. They cost almost nothing and carry almost no risk, which makes the experiment easy to justify even with this little research behind it.

2. Expect a smaller effect than six young men got in a laboratory. In the footbath and heated-sock research, the effect weakened with age, so the older you are, the less you should count on it.

3. A warm bath or shower one to two hours before bed has considerably better evidence behind it than socks do, and it works through the same mechanism.

4. Persistently cold feet is a conversation to have with your provider rather than a quirk to work around. Thyroid, iron status, and circulation are the obvious places to start.

5. If you have reduced sensation in your feet from neuropathy, or known circulation problems, be careful with heated socks, heating pads, and hot footbaths. A burn can happen before you feel it.

6. When sleep has been broken for months rather than nights, ask your provider about cognitive behavioral therapy for insomnia. It's the recommended first-line treatment and it's badly under-supplied, so you may have to ask more than once.

Small comfort measures belong in a bedtime routine on their own merits. Warm feet, a cooler room, and a predictable wind-down are good things to have whether or not a six-person study backs them up.

References

1. Ko Y, Lee JY. Effects of feet warming using bed socks on sleep quality and thermoregulatory responses in a cool environment. Journal of Physiological Anthropology. 2018;37(1):13. PMID 29699592. doi:10.1186/s40101-018-0172-z. Original article: https://link.springer.com/article/10.1186/s40101-018-0172-z

2. Haghayegh S, Khoshnevis S, Smolensky MH, Diller KR, Castriotta RJ. Before-bedtime passive body heating by warm shower or bath to improve sleep: a systematic review and meta-analysis. Sleep Medicine Reviews. 2019;46:124-135. PMID 31102877. doi:10.1016/j.smrv.2019.04.008

3. Shanmugam P, Vijayakumar V, Ravi P, Boopalan D, Kuppusamy M. Does a hot foot bath improve sleep quality? A systematic review and meta-analysis. Alternative Therapies in Health and Medicine. 2025;31(6):42-47. PMID 40492751

4. Raymann RJEM, Swaab DF, Van Someren EJW. Skin temperature and sleep-onset latency: changes with age and insomnia. Physiology & Behavior. 2007. PMID 17070562

5. Ell J, Schmid SR, Benz F, Spille L. Complementary and alternative treatments for insomnia disorder: a systematic umbrella review. Journal of Sleep Research. 2023;32(6):e13979. PMID 37527850. doi:10.1111/jsr.13979 (held in the Yggdrasil Abstract Library)

All citations were retrieved and verified through PubMed.

A note on how to use this

This article is educational and isn't medical advice. It can't account for your history, your medications, or your circulation, and it isn't a substitute for working with someone who knows all three. If your sleep has been poor for months, or your feet are cold enough to bother you, please bring it to your own provider rather than to the internet.

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If this resonates with what you're experiencing and you'd like to explore a naturopathic approach, book a consultation with our clinic.