Hot Tub Benefits
What regular warm-water soaking does, and what the research actually shows
The best-supported benefits of soaking in hot water are better sleep and, in one large long-term study, a lower risk of heart disease and stroke among people who bathed in hot water almost every day. The research is on hot-water bathing in general, not on hot tubs specifically.
Better sleep
A 2019 review in Sleep Medicine Reviews pooled 17 studies of warm baths and showers before bed. Water at 40 to 42.5 °C was associated with better self-rated sleep quality and sleep efficiency. Taken one to two hours before bedtime, for as little as ten minutes, it also shortened the time it took to fall asleep.
The explanation the authors give is body temperature: warm water brings blood to the hands and feet, which helps the body shed heat afterwards, and that drop in core temperature is part of falling asleep.
Heart health
A study published in the journal Heart in 2020 followed 30,076 adults in Japan, aged 40 to 59, from 1990 to 2009. Compared with people who took a hot bath no more than twice a week, those who bathed almost every day had a 28% lower risk of cardiovascular disease and a 26% lower risk of stroke.
This was an observational study. It shows that frequent hot-water bathing and lower risk went together; it does not prove that one caused the other.
What the research does not show
Neither study tested hot tubs. Both looked at hot-water bathing, and the sleep review’s authors note that the research is still limited on the best timing and duration. A hot tub makes a daily soak practical year-round, which is the habit both studies describe — but treat the numbers as evidence about warm-water soaking, not a promise about any product.
If you have a health condition, or any concern about soaking in hot water, check with your doctor or healthcare provider first. Always follow the manufacturer’s instructions.
Sources
- Haghayegh S, et al. “Before-bedtime passive body heating by warm shower or bath to improve sleep: a systematic review and meta-analysis.” Sleep Medicine Reviews, 2019. doi.org/10.1016/j.smrv.2019.04.008
- Ukai T, et al. “Habitual tub bathing and risks of incident coronary heart disease and stroke.” Heart, 2020. doi.org/10.1136/heartjnl-2019-315752
Common questions
Does a hot tub help you sleep?
Research on warm baths and showers found that water at 40 to 42.5 °C, one to two hours before bed, was associated with falling asleep faster and better sleep quality. The studies were of baths and showers, not hot tubs specifically.
Is a hot tub good for your heart?
A study of 30,076 adults in Japan found that people who bathed in hot water almost every day had a 28% lower risk of cardiovascular disease than those who bathed twice a week or less. It was an observational study, so it shows an association, not proof of cause. Check with your doctor if you have a heart condition.
How long should you soak to get the benefit?
In the sleep research, as little as ten minutes in warm water one to two hours before bedtime was associated with falling asleep faster.