Women are more prone to insomnia than men. More women have frequent bouts of sleeplessness (several times a week) than men, and this tendency extends over all periods of life. Not only that, but as people age, the gap between women and men increases. Women under 45 years old have an incidence 1.4 times that of men of the same age. Among older populations, women are 1.7 times more likely to have insomnia.
Many women experience insomnia when they have fluctuations in the serum levels of hormones. These times include during their monthly cycle, pregnancy, and menopause. No cause-and-effect relationship has been established between hormones and sleep latency at a biochemical level, though. It has been shown that hormone supplement therapy for women during menopausal change does decrease reports of insomnia. Bloating, which many women experience as part of their menstrual cycle, contributes to insomnia. Perimenstral insomnia is often a secondary insomnia because the women cannot sleep due to other symptoms such as cramping or headaches.
Premenstrual syndrome seems to cause both insomnia and hypersomnia. Different women experience different symptoms. Sleep restriction has been found to reduce menses-related depression, as has bright light therapy for insomnia. Premenstrual dysphoric disorder also is associated with sleep disruption, although doctors more commonly address the anxiety symptoms than insomnia. Anti-depressant drugs are often prescribed for PDD (and PMS) and often help with sleep problems. If appropriate, doctors may prescribe Z-drugs.
Sleepiness leads to weight gain by discouraging physical activity. Depression leads to overeating. Social expectations of women may contribute to the greater prevalence of sleep disorders. They are more likely to be the primary caregiver than men and more likely to shoulder a larger share of the housework. Researchers have also found that on average women get 5% less deep sleep on average than men.
In general, sleep disorders are more commen in women than in men, and they play out differently, emerging throughout the reproductive life cycle. Women get apnea and restless legs syndrome at a lower rate than men. Premenstrual syndrome seems to cause both insomnia and hypersomnia.
Many anecdotal reports claim that birth control pills cause insomnia in some women, although no formal studies that we know of. It is not surprising, though, that some women should notice an effect of supplemental hormones on their sleep patterns.
Scientists at the University of Munich found young adult women tend to have an earlier chronotype than men of the same age. In general (and this is a large generalization), they tend to be more morning larks. This difference persists until about age 50, after which men and women of the same age have the same chronotype. The fact that the shift happens around the age of menopause suggests sex hormones play a part in women tending more toward the morning lark chronotype.