Naturally fluctuating hormones (menstrual cycle, through pregnancy or menopausal transition) are not related to marked sleep disturbances in women. It is likely, however, that subsets of women will display a central nervous system vulnerability to hormonal fluctuations so that sleep disturbances manifest as a part of a complex of discomforting symptoms. Sleep is impacted directly through the circadian system or brain sleep regulation or through the development of concurrent functional changes and symptoms. Women are susceptible to sleep-related disorders that are also common in men, such as primary insomnia and SBD although the contributing factors and manifestations may not be the same.