Avoiding caffeine, sticking to a schedule and drinking a glass of warm milk are the usual tips for a good night's rest. But the right room temperature can also play a crucial role.

    Studies have found that in general, the optimal temperature for sleep is quite cool, around 60 to 68 degrees Fahrenheit. For some, temperatures that fall too far below or above this range can lead to restlessness.

    Temperatures in this range, it seems, help facilitate the decrease in core body temperature that in turn initiates sleepiness. A growing number of studies are finding that temperature regulation plays a role in many cases of chronic insomnia. Researchers have shown, for example, that insomniacs tend to have a warmer core body temperature than normal sleepers just before bed, which leads to heightened arousal and a struggle to fall asleep as the body tries to reset its internal thermostat.

    For normal sleepers, the drop in core temperature is marked by an increase in temperature in the hands and feet, as the blood vessels dilate and the body radiates heat. Studies show that for troubled sleepers, a cool room and a hot-water bottle placed at the feet, which rapidly dilates blood vessels, can push the internal thermostat to a better setting.

    避免摄入咖啡因，作息规律，喝一杯温牛奶，这些都是保证晚上休息好的小窍门。但是，合适的房间温度也发挥着至关重要的作用。

    研究发现，一般情况下，睡眠的最佳温度是很低的，大约在60-68华氏度范围内。对有些人来说，温度太过低于或高于这一范围，可使其烦燥不安。

    温度处于这个范围内，似乎利于中心体温的降低，而中心体温降低反过来利于睡眠。越来越多的研究表明，在许多习惯性失眠病例中，体温调节发挥着作用。例如，研究人员发现，失眠症患者临睡前体温比睡眠正常者高，这导致觉醒进一步增强，并使得身体重新设置其内部温度控制器，进入睡眠的难度加大。

    对睡眠正常者来说，双手和双脚温度的增加标志着中心体温降低，这是由于血管扩张，身体辐射热量之故。研究表明，对失眠者而言，凉爽的房间加上在脚旁放一个装有热水的瓶子可将身体内部温度控制器设置在较好的值上，而装有热水的瓶子可迅速扩张血管。