You're Throwing Off Your Internal Thermostat
Cold temperatures make us drowsy, and a falling core body temperature helps us get to sleep faster, says Collop. Help this process along by turning down the heat and keeping your bedroom cool (ideally, around 60 to 68 degrees). Opening the windows also helps bring in fresh, oxygen-rich air (unless you live near a freeway), which can contribute to your rest, says John Dittami, an Austrian sleep researcher, biologist and neurologist. However, there's a certain period of REM sleep during which your internal heating and cooling systems change and you become more sensitive to the temperature of the air around you. If you wake up at that point, a once comfortably cool room may now feel chilly. Keep extra blankets within reach so that you won't have to get up to search for them.