Menstruation
About 50 percent of women report more difficulty getting to sleep and staying asleep right before and during their periods, says the National Sleep Foundation. Causes: tender breasts, bloating, cramps, and/or headache. The drop in estrogen prior to your period can also affect sleep, but in another way: With less estrogen you get less rapid eye movement sleep, the type of sleep during which we dream.

Abnormal cycles can also take a toll. Frequent, heavy periods increase your risk of iron deficiency, a chief cause of restless legs syndrome, unpleasant, tingling, achy sensations in your legs that can keep you awake at night. If your periods are few and far between, you could have polycystic ovary syndrome, a hormonal disorder that can go hand in hand with obstructive sleep apnea. Treatment for most menstruation-related sleep problems can be as simple as taking oral contraceptives.

Perimenopause
Sleep disturbances during the transition into menopause are often related to nighttime hot flashes that trigger night sweats. “A woman may thrash and throw the covers off and on in an effort to keep cool, then keep warm,” says Meir Kryger, M.D., a past president of the American Academy of Sleep Medicine. About 70 percent of women going through menopause experience hot flashes at night. The frequency and intensity of flashes vary from woman to woman (and from day to day for the individual); on average, most women have night sweats three nights a week.

Some women find relief with lighter sheets, bedclothes made of special fabrics that wick moisture away from the body, and/or running a fan or air conditioners at night. Short-term hormone therapy can reduce hot flashes, sometimes permanently. Review its benefits and risks with your physician.

Postmenopause
After menopause occurs women finally join men in being at a 4 percent risk for obstructive sleep apnea, a condition in which breathing is blocked by relaxed airway muscles combined with such physical issues as extra tissue in the throat area or enlarged tonsils. After menopause, women are no longer protected by progesterone (which stimulates regular nighttime breathing) and estrogen (which prevents fat from being deposited in the neck, where it can block respiration). Sleep apnea can be mild to severe. It produces spells of oxygen deprivation as well as brief, frequent awakenings (which you may not remember).

Results: You don’t feel well rested even after logging eight hours. Women who snore, smoke, or are overweight are most at risk. Treatments range from breathing devices to weight loss to surgery, but the trick is to be properly diagnosed. “Many doctors still don’t realize that postmenopausal women are as vulnerable as men to sleep apnea. They often mistakenly conclude that sleepiness in a female is depression or stress related,” says Dr. Kryger. “You may have to say to your doctor, ‘I never feel well rested and have been told I stop breathing when I sleep. I’m worried I may have sleep apnea. I think I should be evaluated.’”