How Sleep Affects Cardiovascular Health

In recognition of Sleep Awareness month, we are casting a spotlight on an important but often overlooked fact: Quality sleep has a profound impact on cardiovascular health.

Improving the quality of your sleep could help lower your blood pressure and reduce your risk of heart attack, stroke, Type 2 diabetes, obesity and chronic degenerative diseases like Alzheimer’s and renal (kidney) failure, according to the American Heart Association, which just added sleep to its “Essential” checklist for cardiovascular health. 

Here’s everything you need to know about how sleep affects every aspect of your health, from your immune function to your blood pressure appetite and metabolism, and what you can do to optimize both the quality and the quantity of your sleep.      

How Much Sleep Do You Really Need? 

Most adults need seven to nine hours of sleep each night. However, roughly one in three American adults say they don’t get the recommended amount of sleep, according to the CDC. That’s bad news for your heart, according to pulmonary critical care and sleep specialist Raj Dasgupta, M.D., a spokesperson for the American Academy of Sleep Medicine.

“Sleep is not a luxury — it’s critical to our health,” Dr. Dasgupta says. “People forget that we spend one third of our lives sleeping. If you live to be 90, you will have spent 30 years of your life sleeping. So obviously what’s going on in our body at night affects what’s happening with our health during the day.” 

Pillars of Cardiovascular Health: “Life’s Essential 8” 

The AHA’s new guidelines, which were recently published in Circulation, replace “Life’s Simple 7,” an in-depth questionnaire the organization created in 2010 to assess seven key areas of a person’s cardiovascular health: diet, physical activity, nicotine exposure (including second hand smoke), body mass index, blood lipids (aka cholesterol), blood glucose and blood pressure. 

“I’m very happy to see they added sleep to the list,” Dr. Dasgupta says. “We need to raise people’s awareness about how important sleep is to every aspect of our health.”   

How Sleep Affects Blood Pressure 

When you go to bed at night, your blood pressure usually goes down. This is called “nocturnal dipping” and it’s good for your heart: It gives the organ a reprieve from the constant relentless pounding required to keep the human machine firing on all five cylinders during the day. A decrease between 10-20% is considered normal. 

But people who have sleep problems often don’t experience this dip, which can increase their risk of hypertension, one of the leading risk factors for heart disease and stroke. On average, each five percent decrease in normal nocturnal BP dipping was associated with an approximately 20% greater risk in cardiovascular mortality, according to a recent study in the Journal of Hypertension. 

Keep in mind: truly restorative sleep requires more than just logging eight hours in bed. Important physiological changes happen when we actually go to sleep, Dr. Dasgupta says. “When it comes to our health, both the quantity and the quality of sleep matter.”    

The Importance of Deep Sleep  

During healthy sleep, a person cycles through four stages: non-REM, which has three phases (N1, N2 and N3) and REM (rapid eye movement) sleep. In the third stage of non-REM sleep, N3 (which is also known as Delta or Slow Wave), you enter deep sleep. In this restorative phase, bodily processes slow down, allowing the immune system to devote more energy to fighting infection and repairing tissue.

Deep sleep [the third phase of non-REM sleep] and REM are the two most important stages for all aspects of health, including cardiovascular function, says Dr. Dasgupta. But when you are constantly waking up in the middle of the night — and your body is firing off rounds of the stress hormone cortisol — it prevents you from cycling through these deeper, more restorative stages of sleep. 

Spending less time in REM sleep is associated with a greater overall risk of death from any cause as well as from cardiovascular disease and other diseases except for cancer, according to a new study in JAMA Neurology. 

Poor Sleep Contributes to Obesity

In addition to disrupting deep sleep, elevated levels of the stress hormone cortisol can cause insulin resistance and weight gain. 

Not surprisingly, studies find that the less people sleep, the more likely they are to be overweight or obese and develop diabetes, key risk factors for cardiovascular disease. 

Insomnia and Your Appetite 

At night, when we are asleep, our bodies produce leptin, a hormone that inhibits appetite. “I call it the lose weight hormone,” Dr. Dasgupta says. Being awake stimulates the secretion of ghrelin, or as Dr. Dasgupta calls it, “the gain weight hormone.” 

How to Improve Your Sleep 

If you suffer from medical conditions like OSA (Obstructive Sleep Apnea) or chronic insomnia, experts say you should seek help from a professional. But if you are simply the kind of person who thinks, “You snooze, you lose,” it may be worth reevaluating both your philosophy about slumber and your daily sleep hygiene habits.  Start with these sleep-smart behaviors:  

1. Commit to at least eight hours and stick to a regular sleep cycle. If you know you need to wake up at 7 am, make sure you are in bed by 10:30-10:45 so you have time to relax before bed. Going to bed at the same time every morning and night (including the weekends) helps regulate your sleep wake cycle and optimize circadian rhythms.
2. Start tracking your sleep. A new generation of wearables now makes it easy to monitor not just how long you are in bed, but how long you are actually asleep, and what percentage of the time you spend in each phase of the sleep cycle.  
3. Avoid artificial light for at least 30 minutes before bed (and don’t forget to turn off all the lights). Electronic devices produce stimulating blue light which tricks your brain into thinking it’s daytime. As a result, it suppresses melatonin production in an effort to wake up. A recent study from Northwestern Medicine also showed that night time exposure to even a tiny amount of light could compromise cardiovascular functioning during sleep and increase insulin resistance in the morning.  

4. Don’t eat or drink for at least one hour before bed. Consuming food or liquids too close to bedtime compromises sleep quality, according to a 2021 study in the British Journal of Nutrition. Alcohol may seem to initially help you sleep, but it often disrupts later sleep cycles as liver enzymes metabolize alcohol, according to the Sleep Foundation (it is also a potent diuretic, which explains why you may often find yourself waking up in the idle of the night to use the bathroom). Alcohol increases the risk of sleep apnea by 25%. 
5. Get outside in the morning. Your circadian rhythms are just as sensitive to the beneficial effects of daylight sunshine as they are to the deleterious effects of stimulating blue light at night so open your curtains first thing in the morning, drink your coffee outside on the porch, take your dog for a long walk. Studies show exposure to bright sunshine between 8 am and 10 am can improve night time sleep quality.