If you have trouble falling asleep, listen up. You might fall asleep 15 minutes earlier and wake up far less during the night if you put on a pair of socks at bedtime. To understand why, you first need to grasp the relationship between core（核心）body temperature and sleep. During daylight hours, the human body has an average temperature of 37℃. But your core body temperature drops as much as 1. 2°℃ over one night's sleep. This gradual decrease is a key part of how we sleep. To put it simply, the faster you can lower your core body temperature, the faster you will fall asleep.
One way that your body controls its temperature is through blood vessels （血管）in the skin. If your body is too hot, your blood vessels widen, pushing the warmer blood nearer the skin' s surface, helping it to cool. If your body is too cold, the opposite happens. Your blood vessels narrow, restricting the flow of blood to the surface.
The soles, the bottom surface of your feet, are one of your body's most efficient heat exchangers, since they are hairless and less protected than other skin surfaces. Researchers have shown that warming the feet before going to sleep using a warm foot bath or by wearing socks promotes blood vessel widening, which in turn lowers the body's core temperature faster than going to sleep with cold, bare feet.
Scientists suspect that socked feet have a neurological effect as well. The warm-sensitive neurons（神经元）in the brain become more active when there's a temperature difference between the body's core and the feet. Researchers have found that these neurons become more active as we get sleep and slow down as we wake up, so that warming up the feet before bedtime may give warm-sensitive neurons an extra promotion, making you feel sleepier.
In a small study, researchers found that wearing a pair of special "sleeping socks" not only sped up the coming of sleep, but increased overall sleep time by an average of 30 minutes and cut night-time waking times in half. If you're worried about becoming too warm, look for socks made of natural fibers.
