When you wake up at 4.30 in the morning, your clocks are matched to a cortisol pulse. Viewing bright light in the morning anchors it and entrained it through a circuit that involves cells in the eye and cells in the hypothalamus. This is why it's important to keep the room cool at night to fall asleep. You can always put warm blankets on and put your hand out or your foot out because you actually dump heat through the palms of your hands and the bombs of your feet. If you're in a hot room, you'd have to have like a nice bath next to you to put your hand in.