While many so-called mature adults opt for showers — a good soak might be better for you.
Just ask researchers at the University of Texas, who say taking a warm, well-timed bath before bedtime improves sleep in those with nighttime troubles.
Published in the journal Sleep Medicine Reviews, the multi-study review analyzed over 5,000 research projects that linked water-based activity with sleep quality.
Their results showed the baths were most effective when taken approximately 90 minutes before going to bed and water temperatures between 104 and 109 degrees Fahrenheit were optimal for improving shuteye. This, they say, increased the rate and speed of falling asleep, known as sleep onset latency, by a much as 10 minutes.
“When we looked through all known studies, we noticed significant disparities in terms of the approaches and findings,” says Shahab Haghayegh, a doctoral student at UT’s Department of Biomedical Engineering, who led the study. “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.”
Thermoregulation of the body, controlled mainly by the hypothalamus, works on a circadian rhythm, which also dictates sleep. Our internal temperature usually peaks in the late afternoon and evening, which is about two or three degrees higher than when we sleep. For most, the core body temperature decreases by half or one full degree about an hour before going to sleep, and continues to fall about midway through sleep.
Somewhat paradoxically, though, warm baths help stimulate circulation from the body’s core to its extremities, which actually moves heat out of the core and reduces our internal temperature — thus prepping us for sleep.
Bathing between one and two hours before bed, scientists say, is the sweet spot when it comes to promoting an ideal sleeping temperature. Take the bath too soon before bed and you may be too warm to fall asleep readily and disrupt sleep quality; too long and it may give your core temperature a chance to fall and rise again, nullifying the baths benefits.
Researchers say these findings are “consistent” with our understanding of the effects of water-based passive body heating (PBHWB), but further study is needed due to the “relative scarcity” of reports on the subject.
Meanwhile, the same UT team is also working on a marketable bed system that would work with the individual’s thermoregulatory system to maintain optimal sleep temperatures throughout the night.