How Sleep Affects Your Cardiovascular Health
Poor sleep places stress on your heart and blood vessels. It affects your blood pressure, cholesterol, and heart health.
- Both sleeping under 6 and over 9 hours per night is linked to cardiovascular disease; 7–8 hours a night is the good sleep target to hit.
- Blood pressure normally drops 10–20% during sleep, but failure to dip increases cardiovascular risk regardless of your daytime lifestyle habits.
- Adults sleeping under 6 hours ate approximately 550 more calories per day and had more artery-clogging than normal sleepers.
Cardiovascular disease is the leading cause of death worldwide, by far, and poor sleep is one of its most overlooked and underappreciated causes. This article covers how sleep affects your heart health, from blood pressure and inflammation to cholesterol, weight gain, and blood vessel health.
When looking at things you can change, diet, exercise, medication, and smoking habits are the first port of call (and rightly so). However, sleep rarely gets a mention, despite the solid evidence linking it to cardiovascular health. We now know how bad sleep insidiously damages your heart and blood vessels — night by night, year by year.
Sleep and cardiovascular health: the evidence
Several studies have linked 'sleep duration' (hours of sleep per night) to cardiovascular health, showing that both short (under 6 hours) and long sleep duration (over 9 hours) are predictors of getting or dying from cardiovascular disease. So we’re back to the 7-8 hour sleep-a-night target as the sweet spot for cardiovascular health.[1]
The effects of poor sleep on cardiovascular disease are similar to those of being physically inactive; so it's not a trivial effect either. But, because it’s a completely different question and set of causes, in this article, we’re going to focus on the more common (and easier solved) problem of sleeping too little and sleeping poorly rather than sleeping too much.
How does sleep affect blood pressure?
Blood pressure follows a somewhat predictable pattern throughout the day in healthy people; it dips when you sleep by about 10-20%. Why? Well, scientists think it gives the body a window to rest its heart and blood vessels that have been working hard throughout the day. In some people, blood pressure fails to fall enough (or at all) when they sleep.
People who don't have decreases in their blood pressure when they sleep have an increased risk of cardiovascular disease, irrespective of how healthy they are or whatever they choose to do during the day.
Sleep deprivation also disrupts this natural pattern, not giving your cardiovascular system enough rest. Not sleeping enough can raise your heart rate and blood pressure after just a few bad nights of sleep.[2]
Middle-aged adults who regularly sleep for less than six hours a night tend to have higher blood pressure than those who get eight hours, irrespective of their age, sex, whether they smoked, were physically active, or how much salt and alcohol they consume.[3]
These changes are caused by sleep disrupting your 'autonomic nervous system', which regulates the plumbing of your cardiovascular system.
When your sleep is regularly disrupted, it activates your “fight or flight” response, which in turn increases the stress on your heart and blood vessels. When this accumulates over time, it damages the inner lining of your blood vessels, making them thicker and less flexible. This goes on to increase your blood pressure and stress on your heart (and accelerates the risk of getting cardiovascular disease).
Sleep and your blood vessels
Inflammation
Just a few days of poor sleep triggers inflammation. Sleep, at its core, is really your body’s low-inflammation time. Disturbing your nervous system and hormonal balance when you sleep tips your body into a “pro-inflammatory" state.[2]
Inflammation is strongly linked to cardiovascular disease. In fact, physicians use inflammatory blood markers to predict it. Even slightly elevated inflammation (called “low-grade inflammation”) will damage your blood vessels over time and increase your risk of heart attacks.
Atherosclerosis
Inflammation is one of the main causes of atherosclerosis. Having 'atherosclerotic' blood vessels is often considered the first stage of cardiovascular disease. This is basically the buildup of "plaque” inside your blood vessels (think of a blocked drain pipe). However, it may be years before more serious symptoms start to appear.
Atherosclerosis is the main cause of heart attacks and strokes, which are two of the biggest killers out there. It doesn’t happen overnight; it develops over decades, but poor sleep accelerates it. Those who sleep under six hours a night and sleep poorly have a larger amount and more widespread atherosclerosis.[4]
Sleep, weight gain and visceral fat
Poor sleep promotes weight gain by stimulating your appetite and hunger hormones. These hormones tend to drive you to eat for reward (think sugary, salty, calorie-dense, carbohydrate-based junk foods) rather than for your nutritional needs.[5]
Researchers showed that those who get less than six hours a night ate about 559 more calories a day compared to when they slept normally. The location where you gain fat matters just as much as how much fat you gain. Poor sleep promotes the accumulation of 'visceral' fat, which is stored around your organs and is metabolically active (not in a good way).[6]
Irrespective of your BMI or body weight, high levels of visceral fat are linked to cardiovascular disease and risk factors like insulin resistance, high cholesterol and blood lipids, and inflammation. So it’s not just that poor sleep makes you gain weight (which it does), but it also promotes one of the worst types of fat, which damages your cardiovascular health.
Poor sleep, cholesterol and blood lipids
Researchers have reported links between poor sleep, high cholesterol (particularly the “bad” low-density lipoproteins), high blood lipids and cardiovascular health. However, the effects of poor sleep on your cholesterol and lipid levels aren’t as profound as they are on your blood pressure, inflammation and body weight.[7][8]
The “good” high-density lipoproteins are important for cardiovascular health, as they clean up your blood vessels, carrying them back to the liver to be processed and made into something useful. Less than six hours of sleep a night is associated with lower amounts of “good” cholesterol and larger amounts of fats circulating in your bloodstream.[9]
Lower “good” cholesterol, high “bad” cholesterol and high circulating fats are not signs of a healthy cardiovascular system; they are all independent risk factors for developing cardiovascular disease.
