Women are twice as likely to struggle with insomnia during the summer than in cooler months, according to a National Sleep Foundation surveys. The reason? Later sunsets and warmer, muggier weather block the body temperature drop that’s needed for sound sleep, says Meir Kryger, M.D., author of Can’t Sleep, Can’t Stay Awake. Researchers say even a tiny dip in body temperature can kick-start production of the sleep-inducing hormone melatonin -- and you can accomplish this in just 15 minutes with a cold pack. Try it: Place a cold pack on your skin where blood vessels run close to the surface, such as your wrists, your neck or the crook of an arm or knee, suggest UCLA researchers.