Want better sleep? Try a warm bath or shower 1-2 hours before bedtime, study suggests

Do you struggle trying to fall asleep? Do you feel you don’t get enough sleep and you feel sleepy during the day? You are not alone. The American Academy of Sleep Medicine^[1] has found that one in three American adults have symptoms of insomnia. Data^[2] show there are about 100,000 crashes each year related to drowsy driving which results in 1,550 fatalities and 71,000 injuries. The Institute of Medicine^[3] reported that the long-term effects of sleep deprivation can cause serious health consequences such as hypertension, diabetes, heart attack, stroke and depression.

Many people try over-the-counter or prescribed sleep aids. But is there any way to fall asleep faster and get better sleep without medication?

I am sleep researcher and graduate student in biomedical engineering at the University of Texas. In a recently published study^[4] in collaboration with the UT Health Science Center at Houston and the University of Southern California, colleagues and I showed that a warm bath or shower one to two hours before bedtime can significantly improve your sleep.

Like so many people, I had sleep problems. I struggled falling asleep, I would wake up in the middle of the night, restless and would wake up not feeling rested. I didn’t have a sleep schedule. After I started looking into the data, I realized how many people live their lives in a sleep deprived state. I was not interested in taking drugs, so that made me interested in studying about non-pharmacological methods to help improve sleep.

My team and I reviewed more than 5,000 studies related to bathing and sleep. Seventeen of these studies met our study criteria to explore the effects of warm bath or shower on sleep. We used a statistical procedure for combining data from multiple studies and to find the optimal timing for the bath.

We found that a warm bath, of around 104 and 109 degrees Fahrenheit, for as little as 10 minutes can significantly improve overall sleep efficiency. In other words, a warm bath led to more time spent in actual sleep rather than turning or tossing and trying to fall asleep, compared to usual sleep without taking bath. When scheduled one to two hours before bedtime, a warm bath can also hasten the speed of falling asleep by about 36%.

We also found that whether people reported feeling rested and like they had a great night’s sleep improved by a warm bath or shower, in most of the studies.

Why does the warm bath or shower help? There is science behind it. Our body temperature is not constant during 24 hours. It is higher in the morning and evening, and it is lowest during nighttime sleep. The body temperature needs to drop^[6] to initiate good sleep. When we take a warm bath or shower, the body brings large amount of blood flow to the surface, especially hands and feet. This blood flow brings the heat from the core to the surface and rejects the heat to the environment and causes a drop in body temperature. Therefore, if you take a warm bath/shower at the right biological time – one to two hours before bedtime – it will aid your natural circadian process and improve your sleep.

As a next step, we are now working to design a commercially viable bed system with technology that mimics the effect of warm bath. The bed of the future!

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References

1. ^{^} American Academy of Sleep Medicine (aasm.org)
2. ^{^} Data (www.nsc.org)
3. ^{^} Institute of Medicine (doi.org)
4. ^{^} study (dx.doi.org)
5. ^{^} TORWAISTUDIO/Shutterstock.com (www.shutterstock.com)
6. ^{^} drop (doi.org)
7. ^{^} You can read us daily by subscribing to our newsletter (theconversation.com)