How does sleep affect cardiovascular health?

If you’ve ever lost one night of good sleep, let alone experienced chronic sleep trouble, you know how important sleep is for your ability to concentrate, function, and interact with others normally during the day. You may not know, however, that sleep affects more than just your brain. Irregular or insufficient sleep also increases your risk of cardiovascular disease [1].

The American Heart Association has stated that an irregular sleep pattern, or one that varies from sleeping seven to nine hours at night, is associated with a long list of cardiovascular risks, including obesity, high blood pressure, diabetes (or poor glucose metabolism), hormonal imbalances, inflammation, and coronary artery disease [1]. Getting less than six hours appears to be especially hazardous to your heart health, as those who are sleep-deprived tend to have higher levels of stress hormones and inflammatory markers in their blood, which are also markers of cardiovascular disease risk [1].

What is cardiovascular disease?

As the leading cause of death in the U.S., killing 1 in 4 Americans, it is important to understand and be aware of what cardiovascular disease entails, and which types you have some control over [2]. “Heart disease” and cardiovascular disease are two terms for the same group of health problems: illnesses that affect the heart and its ability to distribute oxygen and nutrients throughout your body via the circulation. The risks of suffering from some types of heart disease can be controlled by diet and lifestyle (including healthy sleep), but you may be genetically predisposed to certain issues, and others still can happen at random. 

Cardiovascular disease can include, but is not limited to:

• Congenital heart disease – a heart abnormality that has existed since birth. Abnormalities could be a hole between heart chambers, a blockage or obstruction of blood flow through the heart, or another defect that affects the delivery of oxygen to the rest of the body (not associated with lifestyle choices).
• Arrhythmia – the rhythm of the heartbeat is irregular, too fast, or too slow. 
• Coronary artery disease – physical damage has occurred in the major blood vessels connected to the heart, or plaque has narrowed the walls of arteries sacrificing their integrity.
• High blood pressure – blood pushes against the artery walls of the heart with more force than what is healthy or can be sustained.
• Cardiac infarction (also known as a heart attack, myocardial infarction, or coronary thrombosis) – the heart stops beating due to muscle damage, causing loss of pulse and blood flow, and consequently quickly deprives the body and brain cells of necessary oxygen.
• Congestive heart failure – a chronic inability of the heart to pump blood in a normal and healthy way.
• Peripheral artery disease – vessels that flow to the limbs and peripheral body have narrowed or are inefficient.
• Stroke – blood and oxygen flow to the brain is restricted, causing brain damage.

How much sleep do I need for a healthy heart?

Different types of cardiovascular disease may be associated with missing certain parts of the sleep cycle or sleep times, but generally seven to nine hours of sleep, during the nighttime, is what’s recommended to support your heart health, according to the CDC [3]. Be advised, too much sleep can also be detrimental to your health. CNN reported results of a study showing that the risk of cardiovascular disease increased by 14% for people who sleep more than 9 hours, and 41% for people who sleep more than 10 hours per night [4].

These numbers may be dependent on your age. The CDC has outlined that sleep recommendations are higher for adolescents and older adults than for those of middle age, and adolescents are not immune to the health consequences of under-sleeping. In fact, the National Sleep Foundation reported that one study found adolescents who didn’t sleep well were at greater risk for developing cardiovascular problems [5]. Adolescents who were under-rested had higher cholesterol levels, a higher body mass index, larger waist sizes, higher blood pressure, and an increased risk of hypertension [5]. As all of these measurements are risk factors for cardiovascular disease, it is easy to see how poor sleep habits at a young age can set a person up for health problems throughout their lifespan. 

Unfortunately, it may not be the quantity of sleep you’re getting that affects your heart health, but the quality. The American Heart Association reports that the amount of time one spends in slow wave sleep (SWS), is a powerful predictor of cardiovascular health [6]. SWS is one of the deeper stages of non-rapid eye movement (non-REM) sleep. It can be measured by sleep scientists using an electroencephalogram and is represented by relatively slow, synchronized brain waves called “delta activity”. In one particular study, participants with the lowest levels of SWS had an 80% increased risk of developing high blood pressure [6].

How can I get more (and better quality) sleep?

Good sleep habits are sometimes referred to as good “sleep hygiene”, and generally it means setting yourself up in the healthiest way to get a good night’s rest.

If you are getting yourself into bed at an early enough hour to sleep seven to nine hours before your wake-up alarm, and still find you aren’t getting enough restful sleep, the National Sleep Foundation has a few behavioral recommendations for things to try. For example, they suggest trying to stick to the same sleep schedule every single night, regardless of workdays or weekends. Inconsistency in your sleep schedule may be interfering with the circadian rhythm and hormonal cycles that help you to feel sleepy before bed and wakeful in the mornings [7]. Resist napping if it means you won’t sleep through the night, and try to exercise daily to make sure both your mind and body are ready for rest when it gets to be bedtime. 

You may have heard that the brain needs to wind down before sleep, that you should follow a relaxing routine, and that electronics should be avoided in the hour before bedtime, but you should also resist your phone and tablet if you wake during the night. The blue light that emanates from your electronic devices actually activates the brain, and will likely keep you up longer [7]. Instead, grab a book (bonus points if it’s boring) and read with a dim light on in another room until you feel the sleepiness return. Try cooling your bedroom at night (between 60 and 67 degrees Fahrenheit), keeping it dark (consider blackout curtains), and listening to white noise (a fan, sound machine, or smartphone app) to best prepare your space for sleep.

Complementary to healthy sleep routines is healthy sleep nutrition. The National Sleep Foundation also says “healthy eating leads to healthy sleeping” [8]. Of course, the opposite seems to be true too. Low SWS times are not only associated with high blood pressure but also with diets low in fiber and high in saturated fat [8]. Too much sugar is associated with more middle-of-the-night wakefulness [8]. 

Eating a balanced diet, rich in whole, fresh foods and B vitamins may not only help you reach and maintain a healthy body weight, but it will also likely help you sleep. B vitamins are directly related to the natural production of serotonin and melatonin, the feel-good neurotransmitter and sleep cycle hormones, respectively. If you’re not getting enough B vitamins from your diet, you may consider adding a B-complex supplement to your nutritional health regimen. 

People with body fat percentages in a “healthy” range are also less likely to experience sleep difficulties like sleep apnea, restlessness, or insomnia, and less likely to fight sleepiness during the day [8]. Therefore, working to stay within a healthy body fat range for your sex, age, and body type may be a key to improving your sleep.

If you still feel like you may need some help drifting off or staying asleep through the night, there are other natural, nutritional changes you can make to promote healthy sleep. Melatonin supplements can be taken before bed to imitate the natural nighttime surge of melatonin release, encouraging a normal circadian rhythm. Alternatively, supplemental minerals like magnesium and potassium may be helpful, as they are both involved in physiological processes that help prepare the body for rest. Metabolic Maintenance even offers a natural supplement, called R.E.M. Maintenance, which combines a number of nutrients all known to promote restful sleep through different mechanisms . 

We hope that these tips are helpful for getting some sleep and supporting the longevity of your heart and overall cardiovascular health. If you would like more ideas and information, please check out the articles referenced above and listed below. Have a restful night and a heart-healthy New Year!

References

1. Harvard Health Publishing. “A good night’s sleep: Advice to take to heart”. Harvard Medical School. September 2017. https://www.health.harvard.edu/heart-health/a-good-nights-sleep-advice-to-take-to-heart
2. Felman, Adam. Everything you need to know about heart disease”. Medical News Today. February 7, 2018. https://www.medicalnewstoday.com/articles/237191.php
3. CDC. “How much sleep do I need?” 2017. https://www.cdc.gov/sleep/about_sleep/how_much_sleep.html
4. WebMD Health News. “Too Much Sleep May Bring Heart Disease, Death Risk”. Health Day. Dec 5, 2018. https://www.webmd.com/sleep-disorders/news/20181205/too-much-sleep-may-bring-heart-disease-death-risk
5. National Sleep Foundation, “How Sleep Deprivation Affects Your Heart”. 2020. https://www.sleepfoundation.org/excessive-sleepiness/health-impact/how-sleep-deprivation-affects-your-heart
6. American Heart Association, “Poor sleep quality increases risk of high blood pressure.” Science Daily. August 30, 2011. https://www.sciencedaily.com/releases/2011/08/110829164644.htm
7. National Sleep Foundation, “Healthy Sleep Tips”. 2020. https://www.sleepfoundation.org/articles/healthy-sleep-tips

National Sleep Foundation. “Eat to sleep better in the New Year.” Sleep.org by the National Sleep Foundation. 2020. https://www.sleep.org/articles/eat-to-sleep-better/