Insomnia and NIH Women's Health Research

Signs, Symptoms, and Risk Factors

Insomnia is a common sleep disorder that is characterized by persistent difficulty falling asleep or staying asleep despite enough time and opportunity to do so and feeling unrested even after a full night's sleep.¹ Symptoms such as lying awake for long periods, waking up often, and feeling unrefreshed in the morning can affect memory, concentration, and mood.² Insomnia may be acute (lasting days to weeks) or chronic, meaning it happens at least 3 nights a week for 3 or more months. Left untreated, chronic insomnia raises the risk of high blood pressure, cardiovascular disease, type 2 diabetes, and depression.^{1 , 3}

Insomnia is classified as primary when it has no other cause or secondary when it results from another condition, such as depression; anxiety; chronic pain; sleep apnea; hormonal disruption; or the use of certain substances, including caffeine, alcohol, or certain medications.⁴ Other factors that increase the risk of insomnia include older age, lower income, high stress, shift work, and an inactive lifestyle.² Racial disparities in insomnia risk also exist, driven largely by experiences of discrimination and psychosocial stress rather than race itself.⁵

Impact on Women's Health

Women are affected by insomnia more often than men across all age groups.^{4 , 6} More than one in four women in the United States experience insomnia symptoms, compared with fewer than one in five men. Hormonal changes play a major role in this difference. Sleep problems are common in the days before menstruation, especially in women with premenstrual dysphoric disorder; during the third trimester of pregnancy; and during perimenopause and menopause, when hot flashes and night sweats often interrupt sleep.^{4 , 7} Conditions that are more common in women, such as depression, anxiety, and fibromyalgia, also raise the risk of insomnia. Women with chronic insomnia tend to face greater long-term health consequences, including higher rates of mood disorders, stroke, and obesity.⁴

Diagnosis and Treatment

Insomnia is diagnosed through a review of medical history and sleep habits, a physical exam, sleep diary tracking, and, sometimes, a sleep study.⁴ Cognitive behavioral therapy for insomnia (CBT-I) is the recommended first line of treatment and has shown sustained effectiveness over other interventions, including medication and sleep hygiene education.^{4 , 8 , 9} CBT-I has also been shown to relieve insomnia during pregnancy, when nondrug approaches are often preferred, and it remains effective when insomnia accompanies another condition, such as depression.^{10 , 11} When insomnia is secondary to another condition, treating the underlying condition is an important part of care and may resolve the insomnia; however, insomnia often persists independently, and treating it can improve the co-occurring condition.^{4 , 11} Sedatives may be used, though their effects can vary between women and men; because women metabolize certain sleep medications more slowly, they may require different doses.⁴ Daily habits can also support better sleep, such as keeping a consistent sleep schedule, limiting caffeine and alcohol in the hours before bed, reducing screen time at night, and getting regular physical activity during the day.

Ongoing Research

Recent work aims to improve access to treatment, including during the menopausal transition, when insomnia is especially common. For example, CBT-I is increasingly delivered online and through trained nurses, extending it beyond specialist clinics, while nonhormonal drugs such as elinzanetant are being studied for their potential to relieve both the sleep disruption and hot flashes of menopause.^{9 , 12} New guidance from the American Academy of Sleep Medicine addresses when to combine medication with CBT-I, and research increasingly shows that treating insomnia directly can improve depression.^{11 , 13} Researchers are also re-evaluating how standard medications affect female sleep physiology; recent evidence that women are more affected by drug-induced insomnia than men points to sex as a factor worth weighing when prescribing medication.¹⁴

The National Heart, Lung, and Blood Institute (NHLBI) is the primary center for research on insomnia and other sleep disorders at NIH, often collaborating with institutes such as the National Institute of Mental Health (NIMH), National Institute on Aging (NIA), and the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Several NIH-funded studies focus on pregnancy and the menopausal transition, both periods when women are especially vulnerable to disrupted sleep. For example, ongoing studies are testing whether CPAP or sleep counseling for mild to moderate sleep apnea during pregnancy lowers the risk of high blood pressure, preeclampsia, and gestational diabetes and whether a mindfulness-based sleep program can improve sleep and reduce the risk of depression during and after pregnancy.^{15 , 16} Another trial asks whether disrupted circadian rhythms contribute to mood, sleep, and energy problems during the menopausal transition and whether timed sleep and light treatments at home can correct these disruptions and improve overall health.¹⁷ A separate multiethnic study follows women through midlife to examine how biological, psychological, and social factors shape sleep and health.¹⁸