Health and Medicine
PUBLISHED
Put the melatonin and magnesium back in the bedside drawer for a moment. While many swear by these sleepy-time supplements, there’s not a huge amount of solid evidence that they promise a good night’s rest. According to some, the answer might be much simpler (and substantially cheaper).
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.Sleep and temperature are closely connected, as anyone who's spent a sweaty summer night tossing and turning will know. Your core body temperature follows a 24-hour cycle tied to the sleep-wake rhythm, falling during the night and rising during the day.
As we drift off to sleep, our core temperature will slightly drop. The body can actively lower the temperature gauge by increasing blood flow to your extremities, namely your hands and feet, which will exude heat like a radiator. Through a feedback loop between body and brain, the drop in core temperature signals that it's time to sleep.
In 1999, a study published in the journal Nature found that having warm feet is the “best physiological predictor for the rapid onset of sleep.” Scientists ran an experiment with 18 human guinea pigs in which they rested in dim, temperature-controlled rooms, snacking at regular intervals while researchers tracked their heart rate, body temperature, skin temperature, melatonin levels, and how sleepy they felt. They found that the best predictor of how quickly someone drifted off wasn't how drowsy they felt or even their core body temperatures, but how warm their feet were.
There are plenty of ways to "hack" this natural feedback loop. Some researchers argue that wearing socks to bed does the trick. Other studies suggest a warm bath or shower an hour or two before bedtime, which, somewhat counterintuitively, helps your body cool down at the right moment.
Alternatively, you might want to take a leaf out of the Japanese playbook: lie on your back, raise your arms and legs, then gently shake your hands and feet for about 30 seconds. This age-old method is known as ゴキブリ体操, or the "cockroach exercise", for obvious reasons. According to its advocates, this produces the same effect of dilating blood vessels in the extremities, drawing heat to the body’s surface, and prompting your brain-body connection to hit the hay.
The method is purportedly promoted by the Nishi Health System, developed in the 1920s and ‘30s by Katsuzō Nishi, an aikido teacher who, coincidentally, was the engineering brain behind the Tokyo subway. Bear in mind, there are no peer-reviewed studies to back up his many claims, but we'd posit that bedtime foot-flapping is an extremely low-risk experiment that's certainly worth a try.
Plus, it won't cost you a thing – besides maybe your dignity.
