Several studies of humans indicate that sleep is strongly linked to the temperature of the sleep environment and resulting thermoregulation in the body. Human physiology is designed for the core body temperature to decrease when we sleep and increase again while we are awake. This internal rising and cooling of body temperature occurs repeatedly in a 24-hour cycle known as the circadian rhythm.
Beginning to fall asleep initiates the process of cooling the body. Hands and feet will cool the fastest followed by the more central locations of the body. The body’s expectation is that it will get cool and remain cool throughout the night until it begins the warming process again around dawn. If the ambient temperature is at a level that pulls the core body temperature up before dawn, the circadian rhythm is interrupted and sleep quality is negatively impacted. It will come as no surprise this type of sleep interruption occurs more frequently during summer months, in warmer climates such as the southern most parts of the United States as well as amongst sections of the population that lack the financial means for housing with climate control.
While sleep is a very personal activity, studies have shown that 65-degrees is the optimal temperature for sleep. This may feel a little chilly to some but helping the body lower its core temperature will generally allow the body to fall asleep faster. If this level feels too cool, make your sleep environment more comfortable by adding blankets or wearing socks.