Take a Warm Bath Before Bedtime for Better Sleep Say Scientists

Posted on July 22, 2019

Bath at Night image

Scientists have found that taking a bath 1 to 2 hours before going to sleep can help you get a better night's sleep. They suggest using water of about 104-109 degrees Fahrenheit. The researchers say the optimal timing of bathing for cooling down of core body temperature in order to improve sleep quality is about 90 minutes before you go to bed.

The research was conducted by biomedical engineers at The University of Texas at Austin. They analyzed data from 5,322 studies to explore the effects of water-based passive body heating on sleep.

Shahab Haghayegh, lead author of the study, says in a statement, "When we looked through all known studies, we noticed significant disparities in terms of the approaches and findings. The only way to make an accurate determination of whether sleep can in fact be improved was to combine all the past data and look at it through a new lens."

The researchers say bathing in warm water stimulates the body's thermoregulatory system. This increases the circulation of blood from the internal core of the body to the peripheral sites of the hands and feet, resulting in efficient removal of body heat and a decline in body temperature. The researchers say this then aids the natural circadian process and increase one's chances of falling asleep quickly and having better overall sleep.

The researchers provided the following explanation on UT News for how the body's temperature changes before, during and after sleep.
Body temperature, which is involved in the regulation of the sleep/wake cycle, exhibits a circadian cycle, being 2-3 degrees Fahrenheit higher in the late afternoon/early evening than during sleep, when it is the lowest. The average person’s circadian cycle is characterized by a reduction in core body temperature of about 0.5 to 1 F around an hour before usual sleep time, dropping to its lowest level between the middle and later span of nighttime sleep. It then begins to rise, acting as a kind of a biological alarm clock wake-up signal. The temperature cycle leads the sleep cycle and is an essential factor in achieving rapid sleep onset and high efficiency sleep.
A research paper on the study was published in the journal, Sleep Medicine Reviews.

Image: Cockrell School of Engineering