为什么穿袜子睡觉入睡更快，还能提高睡眠质量？

科学研究证明，穿袜子睡觉可以让你提前15分钟进入梦乡，晚上醒来的次数也会少得多。双脚的温度跟睡眠质量是密切相关的。要理解其中原因，你需要首先掌握核心体温和睡眠之间的关系。

If you're one of those people who has 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.

如果你入睡困难，注意，穿袜子睡觉可能让你提前15分钟进入梦乡，晚上醒来的次数也会少得多。

To understand why, you first need to grasp the relationship between core body temperature and sleep. During daylight hours, the human body hums along at an average temperature of 98.6 degrees Fahrenheit (37 degrees Celsius). But at night, your core body temperature dips as much as 2 degrees Fahrenheit (1.2 degrees Celsius) over the course of six or seven hours of sleep.

要理解其中原因，你需要首先掌握核心体温和睡眠之间的关系。白天，人体的平均体温为37摄氏度。但是在晚上，在六到七个小时的睡眠过程中，核心体温会下降1.2摄氏度。

This gradual decrease in core body temperature, it turns out, is a key part of the complicated neurobiological dance of falling asleep and staying asleep. And the faster you can lower the core body temperature, the faster you will fall asleep.

事实证明，核心体温的逐渐下降是入睡和保持睡眠这一复杂的神经生物学行为的关键部分。核心体温的下降速度越快，你就越快入睡。

One of the ways that your body regulates its temperature is through blood vessels in your skin. If the brain decides the body is too hot, it will dilate (widen) blood vessels (vasodilation), redistributing warmer blood from the body's core through the rest of the body to cool it down. If the body is too cold, the brain signals the opposite reaction, restricting the flow of blood to the surface (vasoconstriction).

身体调节体温的方法之一是通过皮肤中的血管。如果大脑认为身体太热，会扩张血管，将温暖的血液从身体核心重新分配到身体其他部位，使其降温。如果身体太冷，大脑会发出相反的反应信号，限制血液流向皮肤表面（血管收缩）。

The palms of your hands and soles of your feet are the body's most efficient heat exchangers, since they are hairless and less insulated 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 vasodilation, which in turn lowers the body's core temperature faster than going to sleep with cold, bare feet.

手掌和脚底是身体最有效的散热器，因为与其他位置的皮肤相比，手掌脚底光滑无毛、绝缘性差。研究人员已经表明，睡前泡脚或穿袜子暖脚可以促进血管扩张，这样会比赤脚冷着睡觉更快地降低身体的核心温度。

Scientists hypothesize that socked feet have a neurological effect as well. The brain's "thermostat" is located in a region called the preoptic/anterior hypothalamus (PO/AH). Inside the PO/AH is a type of neuron called a warm-sensitive neuron (WSN) that increases its firing rate when there's a temperature difference between the body's core and extremities like the feet.

科学家们推测，脚上穿袜子也会对神经系统产生影响。大脑的“恒温器”位于视前区-下丘脑前部（PO/AH）。在视前区-下丘脑前部存在热敏神经元（WSN），当身体核心和四肢（如脚）之间存在温差时，该神经元会增加其放电频率。

It's a bit of a chicken and the egg situation, but research has shown that WSN firing rates go way up on the onset of slow wave or "deep" sleep and gradually decrease prior to waking up. So WSNs may play a role in generating the sensation of sleepiness that helps us fall asleep and stay asleep. And if that's the case, warming up the feet before bedtime gives WSNs an extra boost.

这有点像鸡和蛋的关系，但研究表明，热敏神经元的放电频率在慢波睡眠或“深度”睡眠开始时会升高，在醒来之前会逐渐降低。因此，热敏神经元可能在产生睡意方面发挥作用，帮助我们入睡并保持睡眠。如果是这样的话，就寝前让脚变热能给热敏神经元带来额外的动力。

In a small study, Korean researchers found that wearing a pair of special "sleeping socks" not only sped up the onset of sleep, but increased overall sleep time by an average of 30 minutes and cut nighttime waking episodes in half.

在一项小型研究中，韩国研究人员发现，穿一双特殊的“睡袜”不仅加快了入睡过程，而且平均增加了30分钟的总睡眠时间，夜间醒来的次数减少了一半。

If you're worried about becoming too warm while wearing socks in bed, look for ones made of natural breathable fibers.

如果你担心睡觉穿袜子太热，那就找一双透气的天然材质袜子。