Does a warm shower before bed help you sleep?

A warm shower can help you fall asleep a little faster if you take it an hour or two before bed, instead of right before you climb in. If you usually go to bed at 10:30, get in after 8:30 and be out by 9:30. Two small studies measured how fast people fell asleep after a warm bath or foot bath at that time, and on average they fell asleep about 9 minutes sooner ¹. Everyone in those studies had a health problem, like dementia or a brain injury ¹. So don't read too much into the 9 minutes.

Nine minutes isn't a lot, but if you already shower in the evening, all you're changing is when.

When to take your shower

When you take it matters more than how long you stay in. Aim to be out of the shower one to two hours before bed. A warm shower or bath less than an hour before bed, or more than two hours before, didn't clearly help people fall asleep any faster ¹.

For most people, that one-to-two-hour window is already a normal time to shower. It might be right after dinner, once the dishes are done, or before you sit down to watch something. It also gives your hair time to dry before you get into bed.

If you love a hot shower right before bed, it may still leave you feeling like you slept better. In most of the studies that asked people how well they slept, they said they slept better after warm water, no matter what time they had it ¹. Some of that may be the relaxation on top of the heat ¹. To fall asleep a little faster as well, start it earlier, so you're out an hour or two before bed.

How hot, and how long

A 2019 review pulled together 17 studies of warm baths, showers and foot baths before bed ¹. Most of them used water at about 104 to 108°F, or 40 to 42°C ¹. You don't need a thermometer for this. I'd go for water that feels hot on your skin but is still comfortable to stand under.

The review's authors concluded that as little as 10 minutes can help ¹. Longer sessions didn't seem to help any more than shorter ones ¹, so there's no need to stand there until the hot water runs out. Nobody has worked out the best temperature or length yet ¹.

Shower, bath or foot bath

Baths and foot baths were tested far more than showers ¹, but the authors still concluded that any of the three can help ¹. So use whichever fits your evening, and if you have a tub and like a bath, that works too.

If you shower in the morning, I wouldn't move it for this. You can soak your feet in a basin of hot but comfortable water for 10 minutes or more while you watch TV in that same window before bed, and that counts too ¹.

Why warm water helps you fall asleep

It sounds backward that getting warm would help you sleep, since your body cools down at night. As bedtime gets closer, the temperature deep inside your body starts to drop, and it stays low through the night ¹. Your body lets that heat out mainly through your hands and feet ¹. The blood vessels near the skin there can open up wide and carry warm blood out to the surface ¹.

Warm water opens those vessels up even more. When you step out, heat leaves through your hands and feet faster than usual, and the temperature inside you drops further than it would have on its own. That bigger drop is most likely why you fall asleep sooner ¹. Researchers have also noticed that people whose feet are warm at bedtime tend to fall asleep faster ¹. Once you're out, dry off, put on something light and comfortable, and let your body cool down on its own before bed.

If you're too warm in bed

Keep the bedroom cool ²³. If you get into bed and still feel warm, switch to a lighter blanket or put a fan on low. Separate blankets help when you share a bed with someone who runs hotter or colder than you, because you can each pick your own.