psychologist janet kennedy says it's a common complaint, leaving people frustrated, angry, anxious, ruminatingrried, desperate. hot monkey brain or racing thoughts. all of those things. one cause could be cortisol. you see, the body secretes the hormone melatonin at night to help us fall asleep, and then it increases levels of the hormone cortisol in the morning to help us wake up as a part of our normal circadian rhythm. but if cortisol levels are out of whac, it could disrupt sleep and even keep us from falling back asleep. >> the waking up itself is not the problem. you wake up whether you're aware of it or not, but the problem comes in when you're unable to go back to sleep in a reasonable amount of time. >> for women, changes in estrogen and progesterone, say, around perimenopause, may upset cortisol patterns or otherwise impact sleep. talking to your doctor about hormone replacement therapy could be a starting point. other tips that kennedy gives her clients. >> the first thing you do if you're up in the middle of the night is you sit up. so our thoughts are scarier. they're harder to ma