Substantial evidence in recent years suggests the prevalence of sleep apnea in women is higher than previously believed. The Society for Women’s Health Research estimates that one out of every five women has sleep apnea. The majority—nine out of 10—are unaware of their condition and, as such, their resulting increased risk for serious health conditions.
How Sleep Apnea Differs for Women vs. Men
Women and men experience obstructive sleep apnea (OSA), the most common and potentially dangerous type, differently, something that wasn’t completely understood until recently. A 2020 study in SLEEP, authored by Christine Won, M.D., director of the Women’s Sleep Health Program at Yale Medicine New Haven, Connecticut, examined the sex differences regarding obstructive sleep apnea, determining it has to do with two factors:Women are more likely to have sleep apnea during REM sleep than NREM sleep. REM sleep refers to “rapid eye movement,” the dream-like period of sleep in which more brain energy is used. NREM, “non-rapid eye movement,” occurs prior to REM, and is a more shallow sleep and consists of three stages. “Since REM sleep is on average about 20% of our sleep duration, this may mean women have less total number of apneas during the entire night,” says Dr. Won. “But during REM sleep, the apneas tend to be more severe, meaning longer and associated with significant drops in oxygen level.”
Women may be more prone to upper airway resistance syndrome, a disruptive but less severe disorder than sleep apnea. “In this disorder, women still have snoring and collapsible airways, but they do not have frank apneas (a respiratory event where breathing has completely ceased) and do not have oxygen level drops,” she says. Airway resistance still leads to awakenings and sleep fragmentation. Dr. Won notes another difference: Women are more likely than men to wake up from apneas, and suffer greater sleep disruption.
Why Women Are Underdiagnosed With OSA Compared to Men
Dr. Won maintains that women are diagnosed with sleep apnea significantly less than men because of the way the disease is defined. “Obstructive sleep apnea is diagnosed if you have, on average, more than five events per hour of sleep,” Dr. Won says. “Women may be less likely to have sleep apnea during NREM sleep, but have just as much sleep apnea as men during REM sleep.” But, since REM sleep makes up only 20% of total sleep time, the average number of events per night is going to be less in women than men, making it more difficult to diagnose.However, it’s known that sleep apnea during REM sleep, regardless of what’s happening during NREM sleep, is an important risk factor for those with cardiovascular disease. “Therefore, the current way we identify and diagnose OSA may be leading to under-detection of real disease in women,” says Dr. Won.
Additionally, women are more likely to terminate their sleep apnea with an awakening out of sleep. “This means oxygen level drops that accompany sleep apnea may be less observed or less severe in women, and therefore sleep apnea less appreciated in women,” Dr. Won says.
Again, these frequent sleep disturbances caused by sleep apnea may also be important mediators of cardiovascular disease. “Therefore, not catching or counting these types of sleep apnea events when making the diagnosis (like many home sleep apnea tests) may again fail to recognize disease in women.”
How Underdiagnosis Impacts Women’s Health
Because obstructive sleep apnea is more likely to go undetected in women than men, underdiagnosis can seriously impact women’s health. Recent studies show that sleep apnea during REM sleep, regardless of what is happening in NREM sleep, is a risk factor for hypertension and other cardiovascular diseases.“Therefore, even though women may have less sleep apnea events across the entire duration of sleep, since they appear to have just as many sleep apnea events during REM sleep, women may be just as susceptible as men to the ill effects of sleep apnea.”
Sleep apnea can increase the risk of asthma, atrial fibrillation, cancers, chronic kidney disease, cognitive and behavioral disorders, diseases of the heart and blood vessels (heart attack, heart failure, high blood pressure and stroke), eye disorders, metabolic conditions and even pregnancy complications.
Risk Factors for Sleep Apnea in Women
Obesity is a very strong risk factor for OSA in both men and women. In addition, Dr. Won notes that hormone status in women contributes to OSA, which is why women tend to develop it later in life. “Women’s risk of sleep apnea increases markedly post-menopause,” she says. “Female hormones may be protecting women from the NREM sleep apnea that occurs more commonly in men.”Sleep Apnea Symptoms in Women
Because sleep apnea looks different in men and women, it’s not surprising symptoms differ depending on sex. While snoring, gasping, and witnessed apneas are classic symptoms exhibited often by men the signs differ slightly for women.“Women may also have these symptoms, but are also more likely to present with less ‘classic’ symptoms such as insomnia, sleep fragmentation, depressed mood, fatigue or morning headaches,” Dr. Won says.
If you’re experiencing any sleep apnea symptoms, contact your medical care provider as soon as possible. Sleep apnea is generally diagnosed based on medical history, a physical exam and the results of a sleep study, which your doctor can set up for you. Alternatively, they might refer you to a sleep specialist or center to conduct the study.
