Graduate student Shahab Haghayegh has long had trouble sleeping. But when the biomedical engineering student began his doctoral program at the University of Texas at Austin five years ago, his issues worsened. "I would go to bed at 3 or 4 a.m. and wake up at 8 a.m.," he says. The exhausted Haghayegh was getting an average of just 4 or 5 hours sleep a night.
After years of near constant fatigue, he tried a bedtime home remedy: "I started using warm baths," he says. This seemed to help — actually, a lot. These days, Haghayegh says, he's able to fall asleep at midnight, getting three or four more hours of sleep per day.
Taking a warm bath or shower has long been associated with relaxation. But Haghayegh was more interested in scientific evidence, and wanted to see if he could optimize the soothing soak approach. An analysis he and several colleagues conducted of the research literature on the topic, published in the August issue of Sleep Medicine Reviews, suggests that either a warm bath or shower before bed can help a person fall asleep and improve sleep quality — even in the heat of summer. And the optimum time to take one, he says, might be an hour or two before going to bed.
The method is thought to work by augmenting the body's temperature rhythm over 24 hours. Our core body temperature changes throughout the day, as governed by an inborn body clock (though this clock can shift for people who have circadian rhythm disorders, work the nightshift or are jetlagged.) We tend to gradually cool by evening time, before we go to sleep. Augmenting that natural cooling of the body's core temperature, apparently, may be a way to promote sleep.