Heart disease and sleep

Amelia Willson

People are sleeping less than they ever have. In the Western world, the average person gets only 6.8 hours of sleep per night. That’s 1.5 hours less than the average sleeper from 100 years ago and below the recommended minimum of 7 hours per night. At the same time, we’ve seen increases in hypertension, coronary heart disease, diabetes, and other chronic health conditions.

Both sleep deprivation and heart disease are extremely common in today’s modern world. They’re also both connected with higher mortality rates. Heart disease is the leading cause of death in the United States. Meanwhile, poor sleep is one of the largest contributors to heart disease, obesity, cancers, and more.

The relationship between heart disease and sleep is bidirectional. Chronically poor sleep increases your risk for heart disease, and worsens symptoms for those who already have it. Unfortunately, having a heart condition makes it more difficult to get good sleep, creating a no-win situation.

Keep reading to learn more about the connection between sleep and heart health, as well as tips for sleeping better with heart disease.

What is heart disease?

Heart disease, also known as cardiovascular disease, describes a group of health conditions affecting the heart. About one-quarter of deaths each year are attributed to heart disease. It is the leading cause of death in the US. Common types of heart disease include:

  • Coronary artery disease, where damage has occurred to major blood vessels in the heart.
  • High blood pressure, referring to the pressure of blood against the artery walls of the heart.
  • Cardiac arrest or heart attack, where the heart suddenly stops working and the person loses consciousness or the ability to breathe.
  • Congestive heart failure, which is a chronic inability of the heart to pump blood the way it should.
  • Arrhythmia, describing an improper beating of the heart, whether irregularly, too fast, or too slow.
  • Peripheral artery disease, where narrowed blood vessels impede blood flow to the limbs and peripheral areas of the body.
  • Stroke, where a lack of blood supply causes brain damage.
  • Congenital heart disease, which is caused by a pre-existing heart abnormality from birth.

The list of risk factors for heart disease is a long one. It includes age, family history, sex (men are more likely to have heart disease although women’s risk increases during menopause), smoking, poor diet, diabetes, obesity, and more. One major risk factor for heart disease is poor sleep, whether that sleep is too short, too long, or simply unrestful.

Poor sleep as a risk factor for heart disease

Poor sleep is a risk factor for heart disease all on its own, independent from other health issues like obesity, alcoholism, and smoking (although it should be noted that each of these is a cause poor sleep as well). Even for otherwise healthy individuals, disturbed sleep can increase your risk of mortality from cardiovascular issues.

Time and again, research indicates that quality sleep is just as critical for your long-term health as diet and exercise. The overwhelming amount of research establishing the connection between poor sleep and heart disease has led the American Heart Association to issue warnings about it.

Poor sleep can describe a variety of issues, including trouble falling asleep or trouble staying asleep, dependence on sleeping pills, daytime fatigue, and sleep-disordered breathing like snoring.

According to a 2017 study of nearly 13,000 adults, people who experience poor sleep due to any of the above issues have a 71% higher risk of ischemic heart disease (abbreviated as IHD, covering heart attack or angina) and a 45% higher risk of stroke.

disturbed sleep increased stroke and heart disease risk

The researchers even charted the connection between the particular sleep issues and increased stroke or IHD risk:

effect of different sleep disturbances on heart disease stroke risk

Even smaller sleep problems which we might not characterize as “issues” worsen your risk. For instance, the same study found that taking a half hour or more to fall asleep makes you 52% more likely to have IHD and 48% more likely to have a stroke.

Earlier, in 2011, a team of researchers conducted a comprehensive review that summarized the findings from 15 prior studies focusing on heart disease and sleep. In total, these studies covered nearly 475,000 individuals and found that both short and long sleep were risk factors for heart disease:

  • Short sleepers (people who slept fewer than 6 hours) had nearly a 50% higher risk of dying from coronary heart disease (CHD) seven to 25 years later, and a 15% increased risk of stroke.
  • Long sleepers (people who slept longer than 9 hours) had an even higher risk of stroke at 65%, and a lesser (although still worrisome when compared to healthy sleepers) risk of CHD at 38%.

short and long sleep are risk factors for heart disease

Unhealthy sleep has wide ranging consequences, many of which develop into individual risk factors for heart disease, such as sleep deprivation, high blood pressure, invariable heart rate, obesity, and calcium deposits. We’ll review each of these below.

Sleep deprivation

Sleep deprivation has long been linked with poor health outcomes. In 2013, a CDC survey of over 54,000 adults age 45 and up discovered that nearly one-third were sleeping fewer than 6 hours a night. These short sleepers were significantly more likely to have obesity, CHD, stroke, and diabetes than optimal sleepers who slept between 7 to 9 hours. It’s studies like these that have led the CDC to deem sleep deprivation a public health problem.

Sleep deprivation is a common experience for insomniacs, and it’s possible insomnia may cause high blood pressure itself, at least in part. Insomnia often stems from anxiety. Due to their anxiety, people with insomnia tend to be in a constant state of hyperarousal that prevents them from easily falling asleep. This overarousal affects their nervous system and increases their blood pressure.

Even sleep deprivation on a short-term basis is dangerous, as demonstrated by one study of 24-hour shift workers. Many people adhere to this kind of shift work, including firemen, EMTs, and medical residents. Responders like these are in otherwise good health, considering the kind of work they have to perform. However, after one 24-hour shift, the participants had increased blood pressure, increased heart rate, and increased levels of various stress-related hormones like cortisol.

Follow up studies of other kinds of shift workers show similar results. Their odds of developing hypertension are between 1.31 to 1.51 higher than day workers. Further, the correlation only strengthened with time: the longer the shift, the increased risk for hypertension.

Blood pressure and heart rate

Speaking of hypertension, multiple studies show sleep deprivation increases your blood pressure.

Researchers have found that when we don’t get enough sleep, our bodies produce higher levels of C-reactive protein, interleukin-6, tumor necrosis factor-alpha, and other inflammatory agents. Each of these is also linked with heart disease and other chronic health issues like diabetes.

Your risk for both high blood pressure and developing heart disease increases with age. Unfortunately, it also becomes more difficult to sleep well as you age, and the worse your sleep, the worse your blood pressure. The lack of deep sleep that’s common among older adults significantly increases their risk for hypertension:

lack of delta sleep increases blood pressure

People who are sleep-deprived also tend to have both higher heart rates and less variable heart rates than healthy sleepers, and either is bad for your heart.

The chart below shows the difference between healthy and unhealthy fluctuation. The bottom lines (DBP) show blood pressure on a day following insufficient sleep while the top lines (SBP) are after a night of good sleep. The healthier sleepers have more variability in their heart rate than their sleep-deprived peers.

sleep deprivation affects heart rate

Obesity

Obesity is another risk factor for heart disease. Unfortunately, sleep deprivation is also linked with higher obesity rates.

With normal amounts of sleep, your hypothalamus produces the leptin hormone, increasing production throughout the night. Leptin regulates your appetite. Ghrelin, on the other hand, is a hormone that increases your appetite, in particular for fatty and other unhealthy foods. With less sleep, ghrelin production kicks into high gear, increasing your risk for weight gain and the subsequent strain on your heart.

Metabolic syndrome describes people who have high BMI, high cholesterol, and other risk factors for both heart disease and diabetes. One large 2017 study of nearly 17,000 middle-aged people with metabolic syndrome showed that those who slept fewer than 6 hours per night more than doubled their risk of dying from heart disease or stroke within the next 17 years.

Calcium buildup

Both too-long and too-short sleep increase calcium deposits, which are a risk factor for coronary artery disease.

Those who slept fewer than 5 hours a night had 50% more calcium in their coronary arteries, according to a 2015 study of 47,000 men and women averaging 40 years in age. An earlier 2008 study also linked short sleep with increased calcium deposits and higher blood pressure.

Long sleepers fared even worse in the 2015 study. They had 70% more calcium buildup in their arteries. And poor sleep of any kind led to 20% more calcium buildup and arterial stiffness.

Sleep problems in heart disease

As you can see, there are many ways poor sleep increases your risk for heart disease. Unfortunately, once you do develop heart disease, the sleep problems continue. The two main sleep problems affecting people with heart disease are insomnia and sleep apnea.

Insomnia

People with heart disease often experience disturbed sleep, resulting in insomnia (difficulty falling or staying asleep). For example, heart failure is linked with sleep apnea, which also interrupts breathing while you sleep (more on this in the next section). Heart palpitations can also disrupt sleep.

People with heart failure may have bladder issues that require them to wake up during the night to use the restroom. They’re often prescribed diuretics to manage the extra fluid that builds up due to their condition. During the day, the fluid settles in their legs, but at night it creeps up into their lungs, causing chest pain (nocturnal angina) that makes it challenging to fall asleep. Even just lying in bed is uncomfortable. Once they do fall asleep, the fluid slowly builds up in their lungs again, making breathing more difficult until eventually their brain wakes them back up.

Sleep apnea

About half of people with heart failure have some form of sleep-disordered breathing like sleep apnea. Sleep apnea is a sleep disorder where the individual has trouble breathing during sleep. They literally stop breathing momentarily while they sleep, forcing their brain to switch back “on” to get them to start breathing again. Even if they don’t consciously wake up, this constant interruption reduces the overall quality of their sleep and results in sleep deprivation.

Your body responds to these apneic episodes by activating your fight or flight response and increasing adrenaline. With increased adrenaline comes increased blood pressure and increased blood clots – the kind that lead to stroke. One study of 1,475 people found that those with moderate or severe sleep apnea were 3 to 4 times more likely to have a stroke.

Sleep apnea is a risk factor for heart disease because of its affect on your blood pressure and nervous system. Your sympathetic nervous system (SNS) controls your heart rate and blood vessel constriction. Healthy, people without apnea experience a reduction in SNS activity while they sleep, but those with sleep apnea have no relief. They experience increased SNS activity while they’re asleep and while they’re awake. As a result, their blood pressure and heart rate continue to rise, constricting their blood vessels.

If a person has normal heart pressure at the time they are diagnosed with sleep apnea, they are much likelier to develop high blood pressure within the next 4 years. Middle-aged men who have sleep apnea have a higher risk of developing coronary heart disease.

There are two types of sleep apnea: obstructive sleep apnea (OSA) and central sleep apnea (CSA). OSA is much more prevalent than CSA, although both are equally detrimental to your sleep quality and your overall health – heart and otherwise.

OSA can develop whenever there is a blockage or narrowing of the airway, as often happens with obesity. When you are overweight, there is extra fatty tissue in your neck and throat that blocks your airways. OSA is itself a major risk factor for stroke. 75% of people with stroke also have sleep apnea, and the ones with comorbid sleep apnea have worse health outcomes after suffering a stroke than the 25% without.

OSA is correlated with higher rates of coronary heart disease, heart failure, stroke and atrial fibrillation, while CSA is associated with heart failure and atrial fibrillation. Unlike OSA, which stems from a physical blockage of the airways, CSA is caused by a communication issue with the brainstem, which controls your breathing.

Both OSA and CSA interrupt sleep and worsen heart health. Fortunately, treating either typically improves blood pressure and other symptoms of heart failure.

Tips for sleeping better with heart disease

Because the field of research on sleep and heart disease is still relatively young, researchers don’t know if you can reverse the effects of poor sleep on your heart health. However, the better you sleep, the better it is for your heart.

Follow these tips to sleep better with heart disease.

1. Follow a regular sleep schedule.

By going to sleep and waking up at the same time every day, even weekends, you’re reorienting your circadian rhythms to follow a schedule. Overtime, your body will naturally tire or wake up at those times. Make sure your schedule allows for you to get at least 7 hours of sleep.

Pair your new sleep schedule with a calming bedtime routine. A bedtime routine trains your mind to recognize certain activities and behaviors as the prelude to sleep, and if they’re calming, they help reduce your stress levels at the same time, making it easier for you to fall asleep. Your bedtime routine can include activities like aromatherapy, taking a warm bath, brushing your teeth, turning off your phone and TV, or reading a boring book.

2. Make your bedroom an optimal sleep environment.

It’s easier to sleep well when your bedroom promotes sleep. Reserve your bed for sleep and sex only – no work or watching television. Clear your bedroom of clutter and stressful reminders from your waking hours. Keep your bedroom cool – in the mid-60s degrees Fahrenheit – and dark, using blackout curtains and eye mask if necessary.

Those with heart failure can experience fluid build up when they’re lying down, leading to discomfort and sleep-disordered breathing. An adjustable bed that allows you to raise the head of the bed, or a wedge pillow, can alleviate this issue.

3. Exercise and eat well.

Exercise, when done during the daytime, tires our body out so it’s easier to sleep at night. But if you exercise too late in the day, you’ll be too wired to fall asleep. Don’t exercise past the afternoon, and aim to exercise in the early morning if possible to enjoy an extra energy boost for the rest of your day.

Eat healthy. Certain foods, like yogurt, kale, and nuts, have been shown to promote sleep, while others, like sugary junk foods, are bad for it. Eating healthier can also help you lose weight, if obesity is contributing to your heart disease.

Avoid caffeine and alcohol, too. These aren’t good for your heart or your sleep. Caffeine keeps you awake, and while alcohol makes you drowsy at first, it disturbs your sleep and causes early waking.

4. Treat your sleep apnea.

If your stroke is caused or exacerbated by sleep apnea, treating the underlying sleep apnea will prevent stroke and reduce risk of other cardiovascular diseases.

Continuous positive airway pressure (CPAP) machines are the most effective treatment for OSA, while BIPAP therapy is recommended for CSA. These machines require you to wear a mask over your face while you sleep, which opens your airways and enables healthy,regular breathing. You will need to undergo a sleep study to get one of these prescribed.

5. Reduce stress levels.

According to the Women’s Heart Foundation, as much as half of our sleep problems are caused by stress. By reducing your stress levels, you reduce the strain on your nervous system and heart.

Exercise daily to burn off excess energy and stress. Before bed, try keeping a diary where you write down your worries and “flush” them from your mind,” before entering a positive meditation or visualization exercise. Take up yoga.

Avoid electronics in the hour before bed. Not only do these devices have an especially strong effect on your brain (your brain perceives their blue light as sunlight so it tries to keep you awake), but they can also stress you out, whether you’re reading a frustrating work email or watching a super intense television drama.

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