Your body temperature rises and falls during any 24-hour period. It’s usually highest in the early afternoon and lowest at the crack of dawn. As your body prepares to sleep, it loses heat as you get drowsy, explains Dr. Cameron Van den Heuvel in a University of South Australia article about insomnia. He goes on to say that studies of sleep-onset insomniacs have warmer core body temperatures than normal healthy adults. One way to bring on sleep is to lower the room temperature. Similarly, as reported in Time, a study of insomniacs performed by the University of Pittsburgh School of Medicine found that people who suffer from insomnia have more action going on in the frontal lobes of their brains — the planning part — hence the common complaint about the inability to turn off their brains. By literally cooling off their heads, the study subjects fell asleep almost as fast as those without insomnia.