- 1 J Am Coll Cardiol. 2019 Jan 22;73(2):134-144.
- 2 Reuters January 17, 2019
- 3 AMJC January 17, 2019
- 4 Journal of the American College of Cardiology January 2019, Volume 73, Issue 2
- 5 Sleep Volume 33, Issue 08
- 6 National Sleep Foundation, How Sleep Deprivation Affects Your Heart
- 7 Circulation 2015; 132:1329-1337
- 8 Time December 2, 2016
- 9 CDC, Age-Adjusted Percentage Reporting Chronic Health Conditions by Sleep Duration—Behavioral Risk Factor Surveillance System, United States, 2014.
- 10 Harvard Heart Letter September 2017
- 11 Chest. 2010 Aug; 138(2): 434–443.
- 12 Mayo Clinic March 13, 2015
- 13 Curr Diab Rep. 2016 Nov;16(11):106.
- 14 PLOS One July 27, 2017
- 15 U.S. CDC, Sleep and Sleep Disorders
- 16, 17 American Sleep Apnea Association, Sleep Apnea Information for Clinicians
- 18, 19 American College of Cardiology August 2, 2016
- 20 U.S. CDC, Sleep and Chronic Disease
- 21 U.S. CDC, Drowsy Driving
- 22 BBC News October 9, 2013
Your Heart Needs More Than Six Hours of Sleep Nightly
- Sleep is connected with sub-clinical atherosclerosis, the early stages of hardening and narrowing of the arteries
- Those who slept for less than six hours a night were 27 percent more likely to have sub-clinical atherosclerosis than those who slept for seven or eight hours a night
- People with fragmented sleep, meaning they woke up often or had trouble falling asleep, had a 34 percent increased risk of sub-clinical atherosclerosis compared to the longer sleepers
- People who sleep less than seven hours a night also have an increased risk of heart disease, and this is true regardless of other factors that influence heart health, like age, weight, smoking and exercise habits
When you think of methods to boost your heart health, you probably think about diet and exercise, but there’s another component that’s also important: sleep. Getting enough sleep each night, and quality sleep at that, has previously been associated with cardiovascular risk, and recent research also found that sleep is connected with subclinical atherosclerosis.1
Atherosclerosis is a chronic and progressive inflammatory disease that manifests clinically as coronary heart disease. Otherwise known as hardening and narrowing of the arteries, atherosclerosis describes a buildup of plaques in your arteries that can restrict blood flow, leading to blood clots, heart attack and stroke.
At the subclinical level, atherosclerosis is in the early stages and may not yet be causing any symptoms. It’s also possible to reverse the progression at this stage, such that heart disease may be prevented. Toward this end, proper sleep is crucial.
Lack of Sleep or Poor Sleep Increases Your Risk of Subclinical Atherosclerosis
Researchers with the National Center for Cardiovascular Research in Madrid, Spain, used coronary ultrasound and CT scans to measure the artery health of close to 4,000 middle-aged adults and analyzed it according to their sleep duration and quality.
Those who slept for less than six hours a night (very short sleep duration) were 27 percent more likely to have subclinical atherosclerosis than those who slept for seven or eight hours a night.
People with fragmented sleep, meaning they woke up often or had trouble falling asleep, also had a 34 percent increased risk of subclinical atherosclerosis compared to the longer sleepers. There appeared to be a sweet spot, however, as sleeping either too little or too much was associated with heart risks.
Specifically, women who slept for more than eight hours a night had nearly double the risk of subclinical atherosclerosis compared to those who slept for seven to eight hours. To put it into another perspective, the participants, who had an average age of 46 years, had a 5.9 percent or 17.7 percent risk of having a heart attack or stroke in the next 10 or 30 years, respectively.
However, when they slept for less than six hours a night, that risk increased to 6.9 percent for the next 10 years and 20.9 percent for 30 years.2
“[T]his study emphasizes we have to include sleep as one of the weapons we use to fight heart disease — a factor we are compromising every day,” senior study author José M. Ordovás, Ph.D., said in a statement.3 What’s more, he added, “This is the first study to show that objectively measured sleep is independently associated with atherosclerosis throughout the body, not just in the heart.”
While atherosclerosis is often associated with heart disease, it can occur in any of your body’s arteries, with symptoms depending on which arteries are affected. Atherosclerosis in your brain can lead to stroke, for instance, while the condition in your kidneys can lead to high blood pressure or kidney failure, and atherosclerosis in the arteries in your arms and legs may lead to peripheral artery disease.
This implies, then, that proper sleep could play a major role in disease prevention via its role in preventing atherosclerosis alone. The effect is so significant that an accompanying editorial noted that, with additional trials to confirm, sleep could be placed “alongside diet and exercise as a key pillar of a healthy lifestyle.”4
Sleeping Less Than Seven Hours a Night May Also Increase Heart Disease Risk
The link between sleep and heart health is not new, and it could be that even seven hours is just barely enough. People who sleep less than seven hours a night have an increased risk of heart disease,5 and this is true regardless of other factors that influence heart health, like age, weight, smoking and exercise habits. According to the National Sleep Foundation (NSF):6
“One study that examined data from 3,000 adults over the age of 45 found that those who slept fewer than six hours per night were about twice as likely to have a stroke or heart attack as people who slept six to eight hours per night.
It’s not completely clear why less sleep is detrimental to heart health, but researchers understand that sleeping too little causes disruptions in underlying health conditions and biological processes like glucose metabolism, blood pressure and inflammation.”
People who struggle with sleep apnea, which causes frequent nighttime awakenings, often have heart troubles as well. Women with sleep apnea tend to have higher levels of the protein troponin T, which is a marker for heart damage, and are more likely to have an enlarged heart, which is a risk factor for heart disease.7
It’s likely due to lack of sleep that people who work long shifts may also be at risk of heart problems. Researchers from the University of Bonn in Germany took images of radiologists’ hearts before and after a 24-hour shift, during which they got only about three hours of sleep.
Significant heart strain, a precursor to heart problems, was noted following the sleep deprivation.8People who sleep less than seven hours a night are also more likely to have had a heart attack, along with other health problems including asthma and depression.9
Lack of Sleep Increases Your Risk of Health Conditions That Harm Your Heart
Too little sleep probably harms your heart in a number of ways, including not only via atherosclerosis but also by increasing inflammation in your body.
“Sleep-deprived people have higher blood levels of stress hormones and substances that indicate inflammation, a key player in cardiovascular disease. Even a single night of insufficient sleep can perturb your system,” according to Dr. Susan Redline, of the Division of Sleep Medicine at Harvard Medical School.10
Lack of sleep also increases your risk of a number of health problems that take a toll on heart health, including:
•Blood pressure — When you sleep, your blood pressure naturally goes down, a phenomenon known as “nocturnal dipping.” Lack of sleep dampens this natural dipping, which may increase your risk of death from heart disease by at least 20 percent.11
Lack of sleep is also known to increase nighttime blood pressure,12 and high blood pressure at night is an even better predictor of heart disease risk than daytime blood pressure.
•Type 2 diabetes — Too little sleep, poor sleep quality and sleep disorders such as insomnia and sleep apnea have all been associated with diabetes risk, via multiple mechanisms.
“Both physiologic mechanisms such as insulin resistance, decreased leptin and increased ghrelin and inflammation and behavioral mechanisms such as increased food intake, impaired decision-making and increased likelihood of other behavioral risk factors such as smoking, sedentary behavior and alcohol use predispose to both diabetes and obesity, which itself is an important diabetes risk factor,” researchers wrote in Current Diabetes Reports.13 Diabetes, in turn, is associated with an increased risk of heart disease.
•Obesity — Research links not enough sleep with an increased risk of metabolic diseases, including obesity. One study found people who slept for an average of just six hours a night had a waist circumference more than 1 inch (3 centimeters) larger than those who slept for nine hours a night.14 People who are overweight or obese are at an increased risk of heart disease.
Sleep Disorders Hurt Your Heart, Too
Data from the U.S. Centers for Disease Control and Prevention (CDC) suggests one-third of U.S. adults are not getting the recommended seven hours of sleep each night.15 Sleep disorders are one reason why so many struggle to get a sound night’s rest, with sleep apnea being among them.
An estimated 22 million Americans suffer from sleep apnea,16 the most common type being obstructive sleep apnea (OSA), which causes the airway to become blocked during sleep, leading to reduced or blocked airflow. OSA is also associated with obesity, high blood pressure and diabetes, conditions also linked to heart disease, as noted above.
Further, up to 80 percent of moderate and severe obstructive sleep apnea cases are undiagnosed, according to the American Sleep Apnea Association (ASAA), which presents a dangerous scenario because, left untreated, the condition increases the risk of high blood pressure, heart failure, atrial fibrillation, stroke and other heart problems.17
Insomnia is also prevalent, affecting 10 to 15 percent of the U.S. population. Not only is insomnia associated with a higher risk of developing heart disease, but it’s also linked to a greater risk of heart attack, stroke and death associated with heart disease.18
“With more and more evidence for a connection between sleep and cardiovascular disease, some have argued for including sleep disturbances as the 10th potentially modifiable cardiovascular risk factor,” according to the American College of Cardiology.19
Further, when you don’t get enough sleep, it’s not only your heart that suffers. In fact, sleep deprivation, or a lack of quality sleep, has a significant impact on your overall health and may lead to the following:20
|Increased risk of car accidents21||Increased accidents at work|
|Reduced ability to perform tasks||Reduced ability to learn or remember|
|Reduced productivity at work||Reduced creativity at work or in other activities|
|Reduced athletic performance||Increased risk of type 2 diabetes, obesity, cancer, high blood pressure, osteoporosis and cardiovascular disease|
|Increased risk of depression||Increased risk of dementia and Alzheimer’s disease|
|Decreased immune function||Slowed reaction time|
|Reduced regulation of emotions and emotional perception||Poor grades in school|
|Increased susceptibility to stomach ulcers||Exacerbates current chronic diseases such as Alzheimer’s, Parkinson’s, multiple sclerosis and cancer|
|Cutting one hour of sleep a night increases the expression of genes associated with inflammation, immune excitability, diabetes, cancer risk and stress22||Contributes to premature aging by interfering with growth hormone production, normally released by your pituitary gland during deep sleep|
Trouble Sleeping? Here’s What Can Help
Adults need an average of seven to nine hours of sleep a night, with most doing well with about eight. If you have trouble achieving this duration, or you wake frequently during the night, it’s time to take steps to improve your sleep hygiene, starting with your bedroom.
Be sure you’re sleeping in complete darkness, as light (even that from a night light or alarm clock) can disrupt your internal clock and your production of melatonin and serotonin, thereby interfering with your sleep.
In the morning, bright, blue-light-rich sunlight signals to your body that it’s time to wake up. At night, as the sun sets, darkness should signal to your body that it’s time to sleep. Keep the temperature cool, between 60 and 68 degrees F, and eliminate electromagnetic fields (EMFs). Ideally, shut down the electricity to your bedroom by pulling your circuit breaker before bed and turning off your Wi-Fi at night.
This is just a starting point. Other ways to improve your sleep including adopting a neutral sleeping position, going to bed earlier and considering a separate bedroom if your partner is interfering with your sleep. If you’ve already addressed these issues and are still struggling with sleep, see my 33 healthy sleep secrets for a more comprehensive list of strategies for a better night’s rest — your heart, and your health, will thank you.