Your body has an internal clock, called your circadian rhythm. This clock manages your sleep and wake cycles and uses the change in your body’s temperature to prepare you to fall asleep and stay that way. You naturally cool off during the night, but your body temperature slowly raises as you prepare to wake in the morning. That’s what can make you feel hot when you first wake up in the morning – a process that can be exacerbated by a bed that traps heat as you sleep.