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.

    避免攝入咖啡因，作息規律，喝一杯溫牛奶，這些都是保證晚上休息好的小竅門。但是，合適的房間溫度也發揮著至關重要的作用。

    研究發現，一般情況下，睡眠的最佳溫度是很低的，大約在60-68華氏度范圍內。對有些人來說，溫度太過低于或高于這一范圍，可使其煩燥不安。

    溫度處于這個范圍內，似乎利于中心體溫的降低，而中心體溫降低反過來利于睡眠。越來越多的研究表明，在許多習慣性失眠病例中，體溫調節發揮著作用。例如，研究人員發現，失眠癥患者臨睡前體溫比睡眠正常者高，這導致覺醒進一步增強，并使得身體重新設置其內部溫度控制器，進入睡眠的難度加大。

    對睡眠正常者來說，雙手和雙腳溫度的增加標志著中心體溫降低，這是由于血管擴張，身體輻射熱量之故。研究表明，對失眠者而言，涼爽的房間加上在腳旁放一個裝有熱水的瓶子可將身體內部溫度控制器設置在較好的值上，而裝有熱水的瓶子可迅速擴張血管。