When we talk about health behaviors and how they impact our risk for heart disease, the conversation often focuses on diet, exercise, and risky behaviors like smoking. Our healthcare system also encourages preventive screenings, including blood pressure checks and blood tests for cholesterol and glucose control. Yet sleep—a critical health behavior—is often overlooked for this heart health list.
While our medical system recognizes that poor sleep is more likely as we age, sleep is often not discussed as an important general health behavior for young adults; that is, unless you self-report having significant difficulty falling or staying asleep to a healthcare provider. Meanwhile, your body begins to deteriorate after just one night of insufficient or disturbed sleep (sleep deprivation), regardless of age. Sleep, in fact, is a critical bodily function that allows your brain to reorganize neural pathways and your body to repair itself while you rest.
Just as important, sleep behaviors at any age impact your heart health? This is important because poor heart health can lead to cardiovascular diseases (CVD), which are the number one cause of death globally, according to the World Health Organization.
In short, your sleep behaviors and patterns—in addition to various sleep conditions—can be both a source of increased risk for developing heart disease and a warning sign of poor heart health.
Read on to learn more about the relationship between your heart health and your sleep, as well as some changes you can make to your sleep habits and routine that may improve your cardiovascular health.
HOW DOES SLEEP IMPACT MY HEART HEALTH?
Sleep impacts several of the major risk factors for heart disease including:
- High blood pressure (hypertension)
- Poor blood sugar control (diabetes)
- Excessive body weight (obesity)
- Elevated inflammatory markers
Let’s explore each of these risk factors in depth.
HIGH BLOOD PRESSURE
Research demonstrates that both insomnia and sleep deprivation are associated with an increased risk (incidence) for developing high blood pressure (hypertension). Likewise, sleep disruption attributable to restless legs syndrome increases the likelihood of having hypertension. Observational studies demonstrate a strong relationship between the severity of obstructive sleep apnea (OSA) and the risk and severity of high blood pressure (hypertension).
POOR BLOOD SUGAR CONTROL
Among adults with type 2 diabetes, two highly prevalent issues are poor sleep habits and sleep disorders. When researchers evaluated blood sugar control in African Americans with type 2 diabetes mellitus, they found that how long a person sleeps and the quality of their sleep were significant predictors of their blood sugar control. Another study evaluated sleep quality and blood sugar control in an Asian population and found that both poor sleep quality and less-efficient sleep were associated with worse glycemic control in patients with type 2 diabetes. Results from numerous research studies have shown that sleep plays a major role in the regulation of blood glucose levels and insulin sensitivity.
EXCESS BODY WEIGHT
Researchers have found that sleeping less than 7 hours a night is associated with obesity—and, the shorter the night’s sleep, the greater the excess body weight. In one study researchers found that among 500 adults followed for 13 years, individuals who slept less than 6 hours nightly were 7.5 times more likely to have a higher body mass index (BMI), which is the relationship between your weight and height, with a high BMI categorized as being obese. Another study of more than 1,000 people found that adults who slept 7.7 hours had the lowest BMI, with the people who slept both less and more than that having a progressively higher BMI.
Researchers have dug into finding the reasons behind why body weight is connected to poor sleep health. They found that insufficient sleep impacts the hormones that are tied to your feelings of hunger and an increase in your appetite. This leads to overeating, which then impacts blood sugar levels and body weight. In fact, when researchers artificially forced patients into sleep deprivation circumstances they found that the individuals experienced increased hunger, appetite and food intake, with the extra calories eaten exceeding what the body actually needed to support the extra hours awake.
ELEVATED INFLAMMATORY MARKERS
Research has also shown that markers in the blood which signal increased inflammation have been associated with an increased risk for the development of type two diabetes in older adults in the Cardiovascular Health Study, non-diabetic middle aged men, and women. In addition to risk for the development of diabetes, inflammation predicts likelihood of a repeat heart attack, and the future development of cardiovascular disease (CVD) in presently healthy men.
WHICH SLEEP PATTERNS MIGHT BE WARNING SIGNS OF POOR HEART HEALTH?
One of the most confusing connections between heart health and sleep patterns is daytime napping. In a 2019 study from the journal Heart, researchers tracked the sleep habits of nearly 3500 people for five years. The people who napped once or twice a week were 48% less likely to have a cardiovascular event than those who did not nap. Meanwhile, a publication in the journal Sleep compared 11 different research studies that included over 150,000 people total. This comparative, pooled study found that daytime napping of 60 more minutes each day was associated with an increased risk of cardiovascular disease compared to not napping. Yet, napping less than 60 minutes per day was not associated with developing cardiovascular disease. These studies are just two of the countless examples of the differing reports from research on the impact of napping and heart health. The variabilities in the research are present because not all studies account for the many factors that impact sleep such as how often people are napping (frequency) and how long the naps are lasting (duration), and other related factors like daily exercise, stress, etc. Also, different studies use different measurements for planned versus unplanned napping, such as dozing in front of the TV for 5 minutes. Therefore, researchers must carefully compare what each study is and is not measuring before they can make conclusions and recommendations.
Ultimately, an article from the American Heart Association entitled “Enjoy your nap, but be aware of the pros and cons” reports that there is some evidence that short naps of 15 to 45 minutes can reduce fatigue and boost memory. This research has been absorbed by corporate America, with some companies, including Google and NASA, allowing employees to include a short nap time in their work schedule with the hopes that they will be energized and more productive following their nap.
Bottom line: If you are choosing to nap because you find it energizes you, that is different than napping because you cannot stay awake. The inability to stay awake during daytime hours is a sign of health issues that may include a sleep quantity or quality issue or a lack of sufficient oxygen getting to your heart and brain. Either you have insufficient sleep hours at night, sleep that is of poor quality and not leaving your body rested, such as with obstructive sleep apnea, or you have a blockage or anatomical issue that is keeping your body from getting sufficient oxygen and causing you to sleep.
NUMBER OF HOURS OF NIGHTLY SLEEP
In 2018, the European Heart Journal published a large study of over 116,000 people, followed for eight years. The researchers found that among the study participants, an estimated 6 to 8 hours of sleep per night was associated with the lowest risk of death and major cardiovascular events. Sleeping less than 6 hours per night and more than 8 hours per night increased a person’s risk. As the number of hours of sleep increased, the risk for cardiovascular events and death steeply increased. Sleeping 9 to 10 hours per night demonstrated a 17 percent increase in risk, and sleeping more than 10 hours nightly showed a 41 percent increase in risk for a major cardiovascular event or death, as compared to sleeping the recommended 6 to 8 hours per night.
The real question, though, is what causes both too little sleep and too much sleep to increase your risk for heart health issues? Is it that an underlying condition, like sleep apnea (associated with an increased risk for heart disease) causes the person to sleep more and, thus, contributes to the risk for a cardiovascular event?
This is where research is challenging: studies can show us trends and relationships, but they cannot usually (and definitively) show causation.
SO…WHICH SLEEP CONDITIONS ARE HURTING MY HEART HEALTH?
OBSTRUCTIVE SLEEP APNEA (OSA)
Obstructive Sleep Apnea (OSA) is a health condition that involves a partial or complete closure of the upper airway during sleep, which causes the person to temporarily stop breathing. Common symptoms of OSA include snoring, restlessness, morning headaches, daytime sleepiness, and recurrent waking. If you have OSA you are more likely to have high blood pressure than someone who does not have OSA. In fact, three out of four people with resistant hypertension, meaning their blood pressure has not responded to at least three medication interventions, also suffer from OSA. In addition, having OSA is a risk factor for the development of hypertension and is the number one cause of excessive daytime sleepiness due to poor sleep and decreased oxygen levels that occur because of interrupted breathing. In addition to hypertension, people with OSA are more likely to also experience a stroke, coronary heart disease, and irregular heartbeats (cardiac arrhythmias) than people without OSA.
Evidence suggests that treating OSA may result in improvements in blood sugar control and risk for type 2 diabetes, as well as high blood pressure.
The other sleep condition linked to heart health is insomnia, which is described as the act of having trouble falling asleep, having trouble staying asleep, or a combination of both. Occasional insomnia impacts 30 percent to 50 percent of the population. That means at some time during their life, about 1 out of 2 people will be impacted by insomnia. Researchers have identified that chronic insomnia with sleep totaling fewer than 6 hours per night is associated with an increased risk for developing high blood pressure (hypertension). Researchers found that having insomnia and sleeping fewer than 6 hours each night was associated with a 3.59-fold increased risk of having hypertension compared to individuals with insomnia who slept more than 6 hours a night. These data points tell us that as many as half of the people you know are going to experience insomnia at some point—and if they are also sleeping less than six hours a night, they are more likely to have high blood pressure presently or to develop it in the future.
WHAT CAN I DO TO IMPROVE MY SLEEP AND HEART HEALTH?
The most important consideration for your heart health is to see your physician routinely to monitor your blood pressure, cholesterol, blood sugar control, and body weight. It is important to follow their guidelines for diet and exercise to keep these measures under control and to report any new or sudden changes to your health. You should also share any concerns to your healthcare provider about sleep apnea, such as if your partner reports you snore loudly at night or if you routinely wake feeling tired, even after 6 to 8 hours of sleep at night.
Finally, try to reframe how you think about the important factors for heart health and add sleep as a top priority to the list. Begin tonight by taking steps to establish a good sleep routine and set-up a quiet, relaxing sleep environment in your bedroom, including:
- Keeping your bedroom cool,
- Choosing sheets and pajamas that wick away moisture, and
- Choosing a pillow and mattress that support your body.
Due to the interconnectedness between sleep and heart health, making small changes in your routine and making sleep a priority can result in positive changes for many aspects of your health, including improving your heart health and reducing your risk for heart disease!