We’re in the sweltering season now throughout the United States. Hot, humid temperatures make it difficult for many of us to sleep. This isn’t everyone. My husband has what I think is a strange affinity for warm nights. During our July 4 heatwave, he slept like a baby while I sweated and tossed for several nights.
Most of us (my husband excepted) are probably taking steps these days to keep our bedrooms as cool as possible: running air conditioners and fans, keeping curtains and blinds drawn during the day so our sleep environments don’t bake all day in the summer sun.
I was a little surprised to learn how relatively few of us are using one of the simplest, oldest, and most effective ways to cope with hot summer nights: sleeping naked.
According to a National Sleep Foundation survey from a few years ago, roughly 12 percent of Americans sleep naked. The survey compared sleep habits among several countries. The country with the highest percentage of naked sleepers? The United Kingdom, where about 30 percent of people reported sleeping in the nude.
Why can sleeping naked be so helpful to a good night’s sleep? It helps to know a bit about how body temperature affects our ability to sleep at night.
Of course, sleeping in the nude reduces the chances of overheating on a hot and humid night. Sweating, and feeling uncomfortably warm, interferes with our ability to fall asleep and also to stay asleep throughout the night. Studies show that under conditions of high heat and humidity, we’re more likely to sleep restlessly and to wake during the night. We’re also prone to spending less time in the deeper stages of sleep. Both Stage 3 sleep and REM sleep are compromised by heat and humidity. These sleep stages are both important to feeling mentally and physically rested and refreshed the next day. When we’re cheated out of time in deep non-REM sleep and REM sleep, we’re more apt to feel tired, irritable, and distracted.
But there’s more benefit to sleep that can come from sleeping without clothes. That’s because body temperature actually needs to drop slightly in order for us to fall asleep. A slight decrease in core body temperature is one of the natural, biological shifts that our bodies undertake every day. Body temperature fluctuates throughout the day and night, but overall it decreases by about 1-2 degrees during the latter half of the 24-hour day. Our body temperatures typically start to lower in the late afternoon, and continue throughout the evening. That gradual decrease influences our internal circadian sleep clocks, eventually helping to trigger the onset of sleep.
To achieve this drop in core body temperature, the body sheds heat through our skin during the evening. That’s where sleeping naked can come in handy, making it easier for the body to release heat and lower its internal temperature, even on hot and humid nights.
Sleeping naked doesn’t just help avoid being too hot—it may actually help speed sleep along from the inside.
Written by Caitlin Reynolds