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Sleep Medicine

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Sleep and Heart Disease

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The connection between sleeping disorders and heart disease

Sleep is a time of rest for the entire body. Even the heart, which works day and night, naturally slows down during sleep.

That’s why unhealthy heart function (caused by conditions such as heart disease) can deprive the body of restful sleep. Yet, the relationship between heart function and sleep works both ways. For instance, sleep related breathing disorders have been shown to play a major role in causing several types of heart and blood vessel disease.

Sleep and the Heart

Sleep and the Heart

There are two distinct types of sleep:

  • non-REM sleep
  • rapid-eye-movement (REM)

Typically, when you fall asleep you begin in non-REM sleep and spend about 80% of the night in this type of sleep. During non-REM sleep your heart rate, breathing and blood pressure all drop to levels below those occurring while you are awake.

During REM sleep – approximately 20% of your time asleep – both your blood pressure and heart rate can fluctuate. Any time you wake up from sleep (even briefly), your heart rate and blood pressure climb and your heart must work harder. When you wake up in the morning, your blood pressure and heart rate both go up and then stay at a higher level throughout the day.

“Treating certain sleep-related breathing disorders may actually decrease a person’s chances of developing certain cardiovascular diseases”.

Sleep and Heart Disease

Although all aspects of the relationship are not clear, there is definitely a direct connection among sleep, sleep disorders and heart disease.

Some findings:

  • Medical professionals have identified an increased risk of sudden cardiac death in the first several hours after awakening,perhaps due to the increased work demand on the heart that occurs with awakening
  • Various studies have clearly linked sleep-related breathing disorders with increased rates of high blood pressure and increased risk of heart disease and stroke
  • Treating certain sleep-related breathing disorders may actually decrease a person’s chances of developing certain cardiovascular diseases

Heart Conditions Associated With Sleep-related Breathing Disorders

  • Hypertension
  • Coronary Artery Disease
  • Congestive Heart Failure
  • Stroke

Hypertension (High Blood Pressure)

Several studies have shown a link between hypertension and the presence of a disorder of abnormal breathing during sleep called obstructive sleep apnoea (OSA). Not only is hypertension common in those with OSA, but evidence suggests that OSA can lead directly to the development of hypertension.

People with OSA have repeated interruptions in breathing during sleep, caused by the main breathing passage in the back of the throat closing or becoming too narrow. Every time this passage is blocked, breathing stops and oxygen is used up. After a while (usually 10 – 20 seconds, although up to one minutes is not unusual) the breathing difficulty causes a brief awakening, often so short that the person is unaware of any interruption in sleep. The awakening relieves the blockage in the breathing passage and normal breathing resumes, at least until the person falls back asleep, when the entire process can repeat (often hundreds of times per night). The drop in oxygen level from not breathing and the increase in heart rate and blood pressure caused by waking up, puts stress on the heart. These nightly increases in blood pressure eventually lead to permanent increases in blood pressure, even during the day.

It is important to treat hypertension since it is a known risk factor for the development of other forms of cardiovascular disease such as heart attack, heart failure and strokes. But treating hypertension may not be enough if the key reason for a person’s high blood pressure is an unrecognised sleep disorder like OSA.

Hypertension medications, for instance, may not work well if OSA remains untreated. Many people who have difficult cases of hypertension are later found to have untreated OSA and treatment of the OSA can improve hypertension.

For this reason, it is important for your healthcare professional to investigate all the possible causes of your hypertension, including sleep disorders like OSA.

Coronary Artery Disease

There is a direct association between sleep-related breathing disorders and cardiovascular disease. People with OSA, for example, have been known to have higher rates of coronary artery disease (CAD). There are several reasons why this may occur:

  • OSA increases the risk for hypertension which is a known cause of CAD
  • The events occurring during OSA can put excessive stress on the heart and worsen existing disease.

In people with CAS the flow of blood, which carries oxygen to the heart, is limited (due to narrowed arteries). So, if they experience OSA, their blood oxygen levels drop and their heart rate and blood pressure rise, increasing the work required of the heart.

As a result, the amount of oxygen supplied to their heart decreases just as there is demanding more oxygen. Several research studies have shown changes indicating ischemia, or lack of blood flow, on electrocardiogram during apnoeas in people with CAD. However, if recognized, treatment of OSA reduces death due to CAD.

Congestive Heart Failure

Congestive heart failure occurs when the heart is damaged so much that it is unable to pump blood effectively. Disorders of sleep and breathing can cause heart failure and develop as a result of heart failure.

OSA and Congestive Heart Failure

Studies have shown that OSA is a significant risk factor for the development of congestive heart failure. In addition, people who have heart failure from another condition, such as coronary artery disease or hypertension, risk worsening their congestive heart failure if they develop OSA. The heart muscle, already in a weakened state, is unable to handle the additional stress caused by the OSA. However, treating OSA can improve heart function in patients with congestive heart failure.

Symptoms of Obstructive Sleep Apnoea

  • Loud snoring
  • Gasping or choking episodes while sleeping
  • Witnessed episodes of stopped breathing while asleep
  • Excessive sleepiness
  • Falling asleep at inappropriate times
  • Driving or workplace accidents
  • Trouble concentrating, irritability, depression
  • Morning headaches

CSA and Congestive Heart Failure

About 40% of people with congestive heart failure also have a sleep-related breathing disorder called central sleep apnoea (CSA). In CSA there are repetitive episodes of interruptions in breathing during sleep, just like in OSA.

However, in CSA the breathing passage remains open but the person stops making efforts to breathe. Frequent awakenings and drops in the level of oxygen in the blood also occur in CSA. The awakenings increase heart rate and blood pressure, which can worsen heart failure, in turn leading to more CSA and causing a vicious cycle that decreases heart function.

The first approach to treating CSA is to prevent it by treating the heart failure as thoroughly as possible. If CSA is still present, treatments are available to correct the CSA. Treatment of CSA can improve heart function as well as improve sleep quality.

Symptoms of Central Sleep Apnoea

  • Symptoms of congestive heart failure
  • Shortness of breath
  • Difficulty breathing while lying flat
  • Restless sleep
  • Waking up gasping or short of breath
  • Witnessed episodes of stopped breathing while sleeping
  • Unrefreshing sleep
  • Snoring may be absent


During a stroke, the brain is damaged when the supply of blood and oxygen is reduced or cut off. Hypertension is the most common cause of stroke, and, as stated above, OSA can lead to the development of hypertension. In addition, OSA may cause strokes directly since blood flow to the brain is reduced and the level of oxygen drops during apnoeas.

Abnormal breathing patterns during sleep, especially OSA, are also more common immediately following a stroke. Other effects of OSA, such as excessive sleepiness from disrupted sleep and impaired thinking, may hamper a person’s recovery from a stroke.

Effects of Heart Disease on Sleep

As outlined above, sleep-related breathing disorders can directly cause heart disease. Yet, there are effects of heart disease on sleep that, though more subtle, are also important to address.

Shortness of Breath

For instance, patients with congestive heart failure often report difficulty falling asleep or staying asleep because of the shortness of breath that often accompanies heart failure. This shortness of breath is often worse when the patient lies down because blood in the legs flows back into the heart and can overwhelm its ability to pump. Doctors call these symptoms orthopnea (shortness of breath when lying down) and paroxysmal nocturnal dyspnea (waking up from sleep short of breath). The patients who experience these symptoms may feel like they have insomnia since their sleep is interrupted.


In addition to experiencing these complications from heart disease, patients often worry about the long term consequences of a heart attack or chronic heart disease. Such anxiety, by itself, can lead to the development of chronic insomnia.

Taking into consideration all of these plus the direct relationship of numerous heart conditions with sleep-related breathing disorders, it is clear that people with heart conditions need to take special care and seek medical attention in order to ensure their ability to sleep well.

Good Sleep – Health Heart

Many things can be done to maintain a healthy heart:

  • eat a nutritional diet
  • maintain a healthy weight
  • exercise regularly
  • get regular medical check-ups
  • AND get adequate amounts of good quality sleep.

If you have any kind of heart condition, it is I especially important to watch for signs that you may have a sleep related breathing disorder, such as OSA, which could stress your heart. People with OSA are often overweight and experience loud snoring, as well as trouble staying awake during the daytime.

When should I see a health professional?

If you already have hypertension or cardiovascular disease (coronary artery disease, angina pectoris, stroke), talk with your healthcare professional about whether or not you may have a sleep and breathing disorder, such as OSA or CSA.

It is also important that patients with congestive heart failure be monitored for CSA and other sleep disorders at a Sleep Disorders Centre. In contrast to people with OSA, those with heart failure and CSA are commonly thin and may not snore at all.

What happens at a Sleep Disorders Centre?

If your healthcare professional thinks that you have a sleep disorder, he or she may suggest you have a diagnostic test called a sleep study or refer you to a sleep medicine specialist. Sleep studies are usually done in a sleep laboratory, which is a comfortable bed that simulates your normal night’s sleep.

Small sensors called electrodes are attached to your body to measure your sleep, breathing, heart rate and oxygen levels. The sleep specialist will be able to determine whether you have any abnormalities in the quality of your sleep. Your healthcare professional is then given the results and the two of your can decide on the best course or treatment.

Sleep disorders are treatable and treatment can lead to a more healthy heart.

Tips on How to Sleep Well...

There are some general guidelines that help promote good sleep.

  1. + Go to bed only when you are sleepy.
  2. + Get out of bed if you are unable to fall asleep after about 20 minute. Leave your bedroom and do something relaxing. Come back to bed only when you are sleepy.
  3. + Use your bed only sleep, sex and to recover from illness.
  4. + Wake up at the same time every day, including weekends and holidays.
  5. + If you have trouble sleeping at night then avoid naps during the daytime. If you need to take a nap, keep it to less than one hour and take it before 3pm.
  6. + Begin rituals to help you relax before bedtime, such as taking a warm bath or reading for a few minutes.
  7. + Exercise on a regular basis, but do it earlier in the day.
  8. + Maintain a regular daily schedule to keep your brain’s internal clock running smoothly.
  9. + Eat a light snack before bedtime, but avoid a big meal.
  10. + Avoid caffeine, alcohol and cigarettes late in the day.
  11. + Set aside time during the day to get all of your worries out of your system.
  12. + Avoid sleeping pills or use them cautiously under the supervision of a doctor.
  13. + Never drink alcohol while taking sleeping pills or other medications.
  14. + Talk to your doctor or a sleep specialist if you have an ongoing problem related to your sleep.
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