This is the second post in a two-part series about women and sleep apnea.

Our first post, Why Women with Sleep Apnea are Overlooked, investigates the differences in how women experience and report sleep issues and directly addresses the stereotype that sleep apnea is a man’s disease.

In this post, we look at the causes and effects of sleep apnea in women.

As it does in men, sleep apnea in women can cause serious health problems. The sleep disorder increases the risk of heart attack, stroke and early death. Also, the disorder may increase the likelihood of developing type 2 diabetes, obesity and other chronic health problems. Untreated sleep apnea can also lead to cognitive impairments, mood imbalances and metabolic problems.

Yet there are some aspects of the sleep disorder and its risks that appear to be unique for women.

“One of the most important things to realize is that women with sleep apnea have higher mortality rates than men do,” says Said Mostafavi, M.D., the Chief Medical Officer for Advanced Sleep Medicine Services, Inc. and a sleep specialist. “The disorder has a hand in hypertension, diabetes, stroke and other conditions. And there is on the whole a greater risk of death for women. We don’t know exactly why this is, but it is a major concern.”

Sleep apnea can be brought on by changes in a woman’s life

First, women are more likely to experience changes in sleep throughout their lifetime. Two important events—pregnancy and menopause—can both contribute to the likelihood of developing sleep apnea.

Sleep apnea after menopause

When women go through menopause, their menstrual cycle ceases. With that comes a suite of altered hormone levels. In particular, levels of estrogen and progesterone fall. Most women’s bodies adjust successfully, but for some the hormone changes can come with health issues.

Edward O. Bixler of Pennsylvania State University and his colleagues noted in a study published in 2000 that certain hormone level changes might push the body into a state that more readily develops sleep apnea. The evidence for this comes from women who start hormone replacement therapy to counteract some negative effects of their menopause. The researchers found that only 0.5 percent of those who undergo hormone replacement therapy had sleep apnea, far lower that the 2.7 percent of those who experience menopause and don’t take such therapy ^1.

Sleep apnea during pregnancy

Pregnancy can also trigger hormone level changes and associated weight gain, both of which increase the risk of sleep apnea.

“Sleep health during pregnancy is very important for both the mother and the developing baby,” says Karen Cheng, M.D.,  a board-certified sleep specialist based in Orange County, California, who works with Advanced Sleep Medicine Services, Inc. “The most common form of sleep-disordered breathing during pregnancy is obstructive sleep apnea. This condition increases a pregnant woman’s risk for a hypertensive disorder of pregnancy, including preeclampsia, gestational diabetes, and preterm birth of her baby.”

In a 2013 study, researchers at Johns Hopkins University School of Medicine looked at sleep apnea during pregnancy. They tested 105 pregnant women. By the first trimester, 10.5 percent of the women had sleep apnea and by the third trimester that number jumped up to 26.7 percent. Older women and those with a greater body mass index (BMI) in the first trimester were more likely to develop sleep apnea ^2.  

“Third trimester obstructive sleep apnea is common,” the team concluded.

“Evaluation for sleep-disordered breathing during pregnancy is often overlooked,” says Cheng, “But it’s estimated that between 5 and 10 percent of pregnant women will develop obstructive sleep apnea.”

Worryingly, pregnant women with sleep apnea are at risk for high blood pressure, an enlarged heart, blood clots and have a higher rate of admission to neonatal care units and cesarean delivery than pregnant women without the disorder ^3.

“If a pregnant woman presents to the office with significant sleep complaints, including worsening snoring, nocturnal dyspnea, insomnia, restless leg syndrome, and excessive daytime sleepiness, it might be indicative of an underlying sleep disorder,” Cheng says. “Obstetricians should refer women who are having these sleep complaints to a sleep medicine specialist for further evaluation and treatment. Providing help to pregnant women who are complaining about poor quality sleep may not only help them to feel better, but also impact the health of their pregnancy and thus the health of their developing baby.”

Women with sleep apnea are especially sensitive to cardiac health risks

Even without the increased risks during pregnancy or menopause, women with sleep apnea should be aware of some potential health problems they could face. Researchers have already linked the disorder to heart-related issues in the general population, but studies show that women could be more sensitive to heart damage linked to sleep apnea.

In 2013, a small study of 94 men and women in Los Angeles looked at measures of cardiovascular health such as resting heart rate and blood pressure. The researchers showed that women with sleep apnea tended to have more serious heart health impairments than men with sleep apnea did ^4.

There are few studies investigating the link and so still many unanswered questions, explains Dr. Susan Redline, a senior physician at Brigham and Women’s Hospital and the Peter C. Farrell Professor of Sleep Medicine at Harvard Medical School. She has made the link a focus in her research.

In a study published in 2015, Redline and her colleagues tracked 752 men and 893 women. First they checked if the participants had sleep apnea or not through a sleep test or polysomnography (PSG). The team found that about 23 percent of the men and 10 percent of the women had sleep apnea at the start of the study. All were free of heart disease.

Next, the researchers checked in on the participants about 10 to 16 years later. At that time, about 46 percent of the men and 32 percent of the women had either experienced a heart attack, had an enlarged heart or had died due to heart failure. However, only women in the study showed an association between sleep apnea and adverse heart problems.

Specifically, women with moderate to severe sleep apnea were 30 percent more likely to experience those heart problems ^5.

The team also found that women with sleep apnea carried in their blood higher levels of a chemical marker for heart damage called troponin.

Finding that sleep apnea is associated with heart injury and cardiac health problems in women “highlights the importance of sleep apnea screening and treatment for women, a group who often are not routinely screened for sleep apnea,” Redline explains in a press release from Brigham and Women’s Hospital.

Women have more severe sleep apnea during REM sleep

When asked why women might be more susceptible to these ill-effects on the heart, Redline explains that cardiac structure is different between men and women and they also seem to have different responses in their vasculature to the oxygen deprivation of sleep apnea. But ultimately, researchers are still trying to figure the differences out and which are important.

“Women tend to have more severe sleep apnea during their REM sleep,” she says, referring to a stage of sleep associated with rapid-eye movement and dreaming. “REM sleep is also associated with high levels of adrenaline and activation of the sympathetic nervous system. That particular strain of sleep apnea can cause hypertrophy [heart enlargement] over time and lead to heart failure.”

Cognitive impairments and dementia may also stem from sleep apnea 

Heart problems aren’t the only negative health affects that women can face. Redline’s research with colleagues has also shown that women with sleep apnea are at risk for developing mild cognitive impairment and dementia ^6.

Coupling that risk with the increased risk of sleep apnea as women go through menopause is a concern. “Sleep apnea could contribute to cognitive decline in women as they age,” Redline says. “That is a concern for everyone, but women tend to live longer and have higher rates of Alzheimer’s disease in particular, which makes this concern particularly germane.”

How can physicians help women with sleep apnea?

Sleep apnea treatment designed for women

One of the best options for treatment in women as in men is the use of continuous positive airway pressure (CPAP) therapy. However, much of the work put into developing this therapy is based on research on men. That leaves the question: Is CPAP as effective for women with sleep apnea?

“We don’t have any data that CPAP works less well in women,” Redline says. “But still, in both men and women, there can be challenges in adherence to CPAP.” People can have trouble adapting to using a bulky mask. “There is still a real need to identify alternatives or additional therapies,” Redline says. Already, companies are already designing CPAP masks fitted especially for women. Some are smaller, others have a special strap configuration to avoid tangling longer hair.

Researchers with ResMed, a manufacturer of CPAP masks, machines and other products, have taken this idea even further. They have tweaked typical CPAP therapy protocols and accessories to match what experts know about how the disorder shows up in women.

The AutoSet for Her includes a CPAP device and an algorithm that attempts to address sleep apnea characteristics that often show up in women. The algorithm is able to deal with shorter apneas and hypopneas, more events during the REM stage of sleep and a slightly different pressure needed for the therapy ^7.

Education and support for women with sleep apnea

While the research community still has questions about how sleep apnea might differ in women, there is one thing that the science has made clear: Sleep apnea is not a “man’s disease,” it is one that affects us all.

The research shows that there’s a need for experts to recognize and treat the sleep disorder in women. With that goal in mind, Redline and some of her colleagues are active on a patient-centered website called myapnea.org, where patients, their families, healthcare practitioners and researchers can engage together to inform and improve the diagnosis and treatment of sleep apnea.

With the Society for Women’s Health Resources, they are producing a fact sheet for women to download and show to their health care providers that explains the risks that women face related to sleep apnea. The goal is to have a resource that can “actually empower [women] to have a conversation about sleep apnea,” Redline says.

The responsibility also lies with physicians. “To bring up the accuracy of sleep apnea diagnoses in women to the same level as that in men, we need to be asking the right questions,” says Mostafavi. “Ask about sleepiness and fatigue, consider sleep apnea even when your patient is female. The right approach is also to ask questions when the bed partner is present because sometimes they can tell you something that the person with sleep apnea cannot.”

Recognizing this sometimes underserved population in sleep apnea is important. Only then will physicians have the tools to help their patients navigate the other health risks that come with sleep apnea.

Are you concerned that you or a loved one may have sleep apnea?

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Studies cited:

1. Bixler, E.O., et al., (2001). Prevalence of sleep-disordered breathing in women: effects of gender. Am J Respir Crit Care Med, 163(3 Pt 1), 608-613. PubMed
2. Pien, G.W., et al., (2014). Risk factors for sleep-disordered breathing in pregnancy. Thorax, 69(4), 371-377. PubMed
3. Louis, J., et al., (2012). Perinatal outcomes associated with obstructive sleep apnea in obese pregnant women. Obstet Gynecol, 120(5):1085-92. PubMed
4. Macey, P.M., et al.,(2013). Heart rate responses to autonomic challenges in obstructive sleep apnea. PLoS One, 8(10), e76631. PubMed
5. Roca, G.Q., et al., (2015). Sex-specific association of sleep apnea severity with subclinical myocardial injury, ventricular hypertrophy, and heart failure risk in a community-dwelling cohort: The atherosclerosis risk in communities-sleep heart health study. Circulation, 132(14), 1329-1337. PubMed
6. Diem, S.J., et al., (2016). Measures of sleep-wake patterns and risk of mild cognitive impairment or dementia in older women. Am J Geriatr Psychiatry, 24(3), 248-258. PubMed
7. Wimms, A.J., et al., (2014). Obstructive sleep apnea in women: specific issues and interventions. Produced by the ResMed Science Center. PDF

Other posts you may find interesting:

• Why Women with Sleep Apnea are Overlooked
• How Does Sleep Apnea Affect the Heart?
• How Does Sleep Apnea Impact the Brain?
• The Link Between Sleep Apnea and Diabetes