A Wake-Up Call for Women’s Heart Health

By Susan Conova, with reporting by Kristin Bundy, Illustration by Davide Bonazzi, Photographs by Jörg Meyer

Twelve years ago, while nursing her newborn in the wee hours of the morning, Brooke Aggarwal, EdD, desperately searched the scientific literature. “Surely someone has published something on how to get a baby to sleep,” she thought as she pored through PubMed, squinting with exhausted eyes against the harsh light of the laptop. 

What she found validated her lived experience but was not at all reassuring. Having a male infant who was larger at birth and exclusively breastfed was the trifecta that would predispose a newborn to sleepless nights, one study showed. Her son fit all three criteria. “He was pretty much the worst sleeping baby on Earth!” She laughs as she says it … now.

Those restless postpartum nights coaxed Dr. Aggarwal, assistant professor of medical sciences (in medicine), to take a closer look at sleep in her own research, especially among women. “I was in cardiovascular disease research for a long time, but sleep really wasn’t on my radar in terms of a risk factor for cardiovascular disease until my first son was born.”

Women's Work

Poor sleep is endemic in the United States—approximately one out of every three adults reports sleeping six hours or less. Around the time Dr. Aggarwal was struggling with her restless son, researchers were finding that people who reported severe sleep deprivation—defined as regularly experiencing five or fewer hours of sleep a night—were 24% more likely to experience cardiovascular disease. 

The association between sleep deprivation and heart disease generated a big debate among researchers in the field: Did lack of sleep actually cause the increased risk of heart disease, or were the two just correlated? 

It also raised another question: Do more common but less severe forms of sleep insufficiency also affect heart health? 

Dr. Aggarwal joined VP&S scientists Marie-Pierre St-Onge, PhD, and Sanja Jelic, MD, and began enrolling women into a study to answer these questions, with funding from the American Heart Association (AHA). 

The team designed an all-female study, in part because women have historically been excluded from cardiovascular studies and in part because women are at higher risk for poor sleep compared with men. 

Dr. Aggarwal highlights three reasons for the gender disparity. First, women are overwhelmingly the caregivers of children and loved ones who are sick. “We know that the responsibilities of caregiving are linked to sleep disturbances and put women at increased risk for sleep problems,” she says. 

Second, women are twice as likely as men to be diagnosed with mood disorders, such as depression and anxiety, which are linked to insomnia and other sleep problems. 

And third, women experience vast hormonal shifts that affect their sleep at different life stages—during pregnancy and postpartum, as well as during perimenopause and menopause. “All of these different hormonal changes predispose women to increased sleep disturbances,” says Dr. Aggarwal.

Pressure Points

Perhaps unsurprisingly, the results from the researchers’ initial study—which enrolled about 500 women with a wide range of ages and backgrounds—found that sleep problems among women are widespread: 50% of the participants reported some degree of sleep trouble. 

Remarkably, though, even women who were getting seven to nine hours of sleep but reported issues like trouble falling asleep or poor sleep quality were significantly more likely to have elevated blood pressure. The impact of poor sleep on the women’s blood pressure could be large, roughly equal to the impact depression has on heart disease. 

“I was surprised at the findings, because much of the focus in the sleep world up until that point had been on the relationship between sleep disorders and sleep duration and cardiovascular risk,” Dr. Aggarwal says. The women who reported poor sleep despite sleeping the recommended amount of time every night had not only higher blood pressure, but also evidence of inflammation in their vascular system, another predictor of future heart disease. 

“This told us that there is something important about the metric of sleep quality, and this should be taken seriously, especially in women. And we needed to start measuring it.”

Life Stages

Among postmenopausal women in the same study, the Columbia investigators found an even stronger association between poor sleep and high blood pressure. 

Cardiovascular disease is the single biggest cause of death among women, whose risk for this disease spikes after menopause. The increase is not just due to age, but also to changes in body fat, vascular health, and cholesterol and other lipids that accompany the menopause transition.

In 2020, the AHA published a scientific statement, co-authored by Dr. Aggarwal, about the role of menopause in driving heart disease in women, underlining the significance of the transition years and emphasizing the potential importance of risk-reducing interventions during this stage of life.

“In our Columbia study, I was very glad that we were able to examine our data by a woman’s life stage, rather than just chronological age,” she says. “It told us that the menopause transition may be a critical time to improve sleep to reduce the risk of heart disease. And it prompted us to recruit a new cohort of women between 45 and 55 years of age to look more closely at these questions.” 

Results from that cohort—involving more than 300 women across the United States—are just starting to be published. So far, the study has revealed that significant sleep disturbance in this age range is incredibly common: Approximately 75% of participants reported a sleep problem, including trouble staying asleep—a hallmark of menopausal hormone fluctuations. Women in this age range with poor sleep quality were three times more likely to have poor cardiovascular health scores (as measured by the AHA’s guidelines known as Life’s Essential 8). 

Further analysis suggests that the connection between poor sleep and heart health among these women may work via sleep’s relationships with body weight, diet, blood pressure, and blood glucose levels. 

“Women, especially menopausal women, have been underrepresented in cardiovascular research studies,” Dr. Aggarwal says. “Studies like ours are showing where we may be able to intervene.”

Mechanistic Insights

Though the team’s studies established associations between mild sleep deficiencies and heart health among women, the studies were not designed to determine if poor sleep could cause heart disease. 

“Epidemiological studies that find associations could be tainted by many confounders that cannot be identified and adjusted for,” says Dr. Jelic, who is director of the Center for Sleep Medicine at Columbia and professor of medicine in the Division of Pulmonary, Allergy, and Critical Care Medicine. “Only randomized controlled studies can determine if this connection is real and what changes in the body caused by short sleep could increase heart disease.” 

A mechanistic insight came from the team’s initial study, which took samples of endothelial cells from the veins of approximately two dozen participants to look for a proinflammatory protein implicated in the development of cardiovascular disease. Among those participants, women who reported mild sleep disturbances had greater levels of endothelial inflammation.

“It suggested to us that mild sleep problems could possibly initiate the vascular endothelial inflammation that’s a significant contributor to cardiovascular disease,” says Dr. Jelic.

With Dr. St-Onge, who is an associate professor of nutritional medicine, Dr. Jelic designed a study to determine if sleep was indeed causing vascular inflammation or other changes known to promote heart disease. Dr. St-Onge’s early work focused on the role diet plays in cardiometabolic health. She moved into the field of sleep research to see if poor sleep affected heart health by promoting unhealthy eating habits and weight gain. 

In designing their study, the researchers made a break from most previous sleep intervention studies, which typically examine the physiological effects of a few nights of profound sleep deprivation.

“But that’s not how people behave night after night. Most people get up around the same time each day but tend to push back their bedtime one to two hours,” Dr. Jelic says. “We wanted to mimic that behavior, which is the most common sleep pattern we see in adults.”

For their more naturalistic study, the researchers recruited women with normal sleep duration of seven to nine hours per night and asked them to sleep just six hours a night over a six-week period. Dr. Jelic collected participants’ endothelial cells to analyze changes in inflammation levels. Dr. St-Onge collected data on insulin resistance and blood pressure.

Finding volunteers for the study was a difficult task.  “When we do these types of studies where we adversely impact sleep, we need to recruit people who have good sleep to begin with,” Dr. St-Onge says. “Finding postmenopausal women who reported having good sleep was especially challenging.” 

“Frankly,” she adds, “many postmenopausal women were also reluctant to restrict sleep for six weeks. You’re at that stage in your life where you’re like, ‘Yeah, no, not doing that.’ But we did have 11 postmenopausal women out of 38 participants who agreed to participate.”

These studies pointed to mild sleep restriction as a cause of multiple known factors that increase heart disease. Mild sleep restriction for just six weeks increased oxidative stress in vascular endothelial cells—a precursor to vascular inflammation and dysfunction that can lead to cardiovascular disease; the reduction in sleep also increased blood pressure and insulin resistance, a known driver of heart disease.

“This is some of the first direct evidence to show that mild chronic sleep deficits cause heart disease,” Dr. Jelic says.

Next Phase: Sleep Variability

A big win for sleep awareness came in 2022 when the Columbia studies, among others, helped convince the AHA to add sleep duration (seven to nine hours per night for most adults) to their Life’s Essential 8 checklist of metrics to promote good cardiovascular health.

“I think now, in 2025, many clinicians are taking sleep seriously as a modifiable factor that can improve heart health,” Dr. Aggarwal says. “They are more willing to ask patients at least one question: ‘How is your sleep?’ And that is fantastic. Additionally, patients are more aware and often bring it up themselves.”

Though sleep duration has now been embraced as a risk factor for cardiovascular disease, other aspects of sleep and their cardiovascular implications remain to be studied.

According to some of the most recent research on sleep and heart health, the heart particularly likes consistent sleep. Aggarwal cites a Harvard study that followed older adults for five years, finding that participants with the most irregular sleep schedules were nearly twice as likely to develop heart disease as those with more regular sleep patterns. What’s more, a study by Drs. St-Onge and Jelic found that women’s weight improved when they reduced bedtime variability.

“It’s not known why an irregular sleep schedule affects the heart, but sleep inconsistency may disturb the body’s circadian rhythms,” Dr. Aggarwal says. “Heart rate, blood pressure, and other cardiovascular functions vary with the time of day and may become disrupted by inconsistent sleep.”

Most women now report a high day-to-day variability in sleep duration and timing as their habitual sleep pattern.

“Even going to sleep or waking up more than 60 minutes off your usual schedule from day to day could potentially impact the heart over time,” Dr. Aggarwal says, “and may be more important than sleep duration.”

The Columbia researchers are now expanding their investigations into sleep variability. Dr. St-Onge is currently evaluating how reducing bedtime variability affects glycemic control and body composition in adults with prediabetes.

And this year, Dr. Aggarwal began recruiting for a new study to more closely examine sleep variability and quality among women and how they may affect overall cardiovascular health. 

With the goal of recruiting more than 800 women, the new study is one of the largest to evaluate sleep and heart health over the long term. It’s also one of the few long-term studies to look at women going through the menopause transition, determining how their sleep changes over the years and how that affects cardiovascular disease risk, says Dr. Aggarwal.
“We’re essentially measuring all important cardiovascular health metrics to see if they’re associated with different sleep patterns,” says Dr. Aggarwal.

With the new study, Dr. Aggarwal hopes to potentially expand the AHA guidelines and eventually inform how physicians and patients talk about sleep. “If we do find that sleep quality and variability are just as important as, or more so, than sleep duration, then we will advocate for those aspects of sleep to be part of clinical encounters and public health recommendations to help improve cardiovascular health,” she says.

Dr. Aggarwal’s children are now 12 and 10. She sleeps a lot better than when they were little. She goes to bed at 9 p.m. and rises at 5 a.m. every day, which she says matches her natural preference as a morning person. During those morning hours, she often works on her laptop while the children get their last couple of hours of shut-eye before school. One of her newest projects involves studying women, sleep, and heart health in the first six months after giving birth. Postpartum women were considered vulnerable when she started her research. But now, there is new energy to uncover details of the sleepless lives of exhausted new mothers and how their health may be affected. “We just submitted the internal review board protocol to survey postpartum women about their sleep. We look forward to having more information on that,” Dr. Aggarwal says. Art (and science) really do imitate life.