Why do we need to pay more attention to women's sleep health?
Women sleep differently than men. They can take longer to fall asleep, tend to be more sleep deprived, are at increased risk for insomnia, and often report different symptoms than men. There are biological and physiological reasons for why women sleep differently.  The sex chromosomes and gonadal hormones primarily contribute to the biological and physiological differences, and these are called sex differences. Also, a combination of environmental, social and cultural influences on these biological factors in men and women contribute to gender differences.  So hormonal and physical changes at different times during a woman's life span can impact her sleep health and lead to gender-specific sleep disorders. 
We know from animal studies that estrogen has a greater influence on normal sleep in female rats compared to male rats. [4, 5] Sleep disorders such as insomnia and restless leg syndrome (RLS) pose a greater risk for women than men and most likely coincide with hormonal changes.  For example, women are at greater risk for developing insomnia at the start of menses and menopause.  Pregnancy poses a greater risk for RLS, and this risk continues with subsequent pregnancies. It further increases two-fold with menopause. Interestingly, pregnant women have twice the risk for RLS compared to women who have never given birth and men. 
Sex differences also have other important clinical consequences. Last year, the Food and Drug Administration (FDA) reduced the dosage of Ambien for women by half. Ambien is a commonly prescribed sedative for women.  This change in dosage was based on the discovery that women were metabolizing the same dose of drug 50 percent slower than men, which resulted in higher amounts of Ambien in women's bloodstream leading to more excessive sleepiness in women compared to men.  This historic move by FDA underscores the importance of studying sex differences and consequently paying more attention to women's health.
Normal sleep in women is affected by hormones during menses, pregnancy/lactation, perimenopause and post-menopause, and can lead to sleep disturbances or sleep disorders during these periods.  Psychosocial issues also can impact sleep health in women more often than men. Depression, pain and stress can all cause sleep disturbances and the risk of all three conditions higher in women than in men. [2, 9]
Female shift workers report poor sleep quality compared to their male counterparts and are at increased risk for breast cancer, shorter menstrual cycles, miscarriage and sub-fertility.  There needs to be a greater understanding on how to integrate these unique psychosocial issues into biological research. Other physical conditions such as overactive bladder and pain can cause disrupted sleep in women. [2, 11] Disrupted sleep in older women can result in poor daytime function, physical performance and functional limitations leading to difficulty with daily activities.  These psychosocial issues need to be considered for women during diagnosis and treatment of sleep disorders.
Another problem is the diagnosis of sleep disorders in women. Some sleep disorders in women are under-recognized, misdiagnosed and mistreated, highlighting a gender bias in clinics.  Lack of awareness among physicians and misinterpretation of women's symptoms are some of the reasons for misdiagnosis and mistreatment.  Therefore, it is essential to design and use gender appropriate tools to screen and diagnose sleep disorders in women.
Several major gaps continue to exist in sleep research for women. This is in part due to the early work focused on sleep apnea, which primarily affects men. In addition, lack of awareness of sex differences in sleep research has contributed to this knowledge gap.
The Society for Women's Health Research (SWHR) is committed to improving women's health through research, advocacy and education. SWHR conducted a roundtable discussion with nationally renowned sleep experts in October 2013 in Washington, D.C. The discussions at the meeting showed us much more needs to be known about women's sleep health.
To study this issue further, SWHR has launched an interdisciplinary network on sleep to improve our understanding of the importance of sleep in women, focusing on preventing sleep disorders and related conditions. Check out our progress as we start this exciting initiative at www.SWHR.org.
By Monica Mallampalli, PhD, MSc., SWHR director of scientific programs
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