What Causes Rapid Heart Rate While Sleeping?

Waking up with a racing heart can be an unsettling and frightening experience. However, such heart palpitations are common and are often harmless and nothing to worry about. There are a number or reasons why you may awake with your heart racing, which could be the result of everyday activities or underlying causes.

The following are some of the main reasons why you may experience a racing heart while sleeping.

Sleep Apnea

Sleep apnea is a disorder in which your sleep is frequently interrupted due to breathing difficulties.

Obstructive sleep apnea is the most common form of this disorder, in which the upper airways are repeatedly blocked, causing the brain to prompt the body to wake for air.

These pauses in breathing can happen many times overnight, leading to a drop in blood oxygen levels. In response, there is an increase in blood pressure, placing additional stress on the heart to pump blood which can result in the heart racing faster. Further sleep apnea symptoms include:

  • Loud snoring
  • Gasping for air when you awake
  • Excessive daytime fatigue
  • Morning headaches
  • Dry mouth in the morning

Without treatment sleep apnea can increase the risk of serious health complications. However, once diagnosed it can be treated, reducing these risks as well as reducing the risk of a racing heart while sleeping.

Sleep Deprivation

Sleep deprivation is often the result of undiagnosed sleep apnea, as well as other issues such as stress and insomnia. Modern lifestyle can also endanger how much sleep we receive, as many of us rarely get the required 7 to 8 hours recommended each night.

Evidence suggests sleep deprivation can also cause your heart to race. Indeed, a study by the Radiological Society of North America observed an increased heart rate in study participants from just 24 hours of sleep deprivation.

Diabetes or Hypoglycemia

High blood sugar levels can trigger the release of stress hormones and can cause your heart to race. Also, processed sugars, eating refined carbohydrates like white bread and pasta can cause in a spike in blood sugar levels.

Hypoglycemia is when blood sugar levels are low, causing the body to release the hormone epinephrine which can induce heart palpitations. The continued impact of high and low blood sugar levels can increase someone’s risk of cardiovascular issues.


A racing heart can be a side effect of certain medications, particularly those containing stimulants. Over-the-counter medication which can cause heart palpitations include:

  • inhaled steroids
  • some thyroid medications
  • amphetamine
  • pseudoephedrine, often found in cold medications
  • ADHD medications


When struggling with a cold or a fever, the body works to regulate the changes in body temperature. You may experience shivering from a fever as the skin’s blood vessels expand and contract -- as the body strives to regulate its temperature. 

Heart palpitations can result from the extra effort required to maintain a regular body temperature.


Caffeine is a stimulant and consuming too much can lead to heart palpitations. Caffeine is present in everyday items such as coffee, tea, energy drinks and some sodas. 

Along with a racing heart, you can experience a feeling of jitteriness from too much caffeine, as well as anxiety and problems sleeping.


Drinking too much alcohol before you go to bed can also see you awake with heart palpitations, and the more you drink the faster the heart may race. It can take a while for the effects of alcohol to wear off -- and for the heart to return to its normal beating rate.


An overactive thyroid can be another underlying cause of a racing heart. This happens when the thyroid gland produces too much of a hormone called thyroxine -- which in turn can accelerate your metabolism. 

This increase in the rate of metabolism can cause your heart palpitations.

Another potential outcome of an overactive thyroid is weight loss. Further symptoms of this condition include:

  • night sweats
  • intolerance to heat
  • increase in appetite
  • menstrual irregularities


Anemia is the result of a lack of healthy red blood cells to transport the amount of oxygen the body requires to function properly. This can happen because the body is either not producing enough red blood cells to cope or destroying the necessary cells.

Your heart may have to work harder to supply the oxygen the body needs, and this can lead to a rapid heart rate. As well as heart palpitations, other signs of anemia include fatigue, shortness of breath, headaches, feeling weak and poorer levels of concentration.

Anxiety/Panic Attack

Anxiety and stress can also cause heart racing from the stress hormones the body releases. Your anxiety level, along with your symptoms, evidence of your stress level, are prominent symptoms. Along with sleeping problems and a racing heart, anxiety can cause you to feel short of breath, worry excessively and find it difficult to concentrate.

When Heart Palpitations Persist

The occasional racing heart when sleeping is actually quite common and not normally something to worry about. However, if it is accompanied by dizziness and chest pains it could be the sign of a heart attack -- and you should seek emergency medical assistance.

If your heart palpitations become a regular occurrence you should consult your doctor to check for underlying causes. 

This may include testing for sleep apnea, which once diagnosed can be treated to help improve your sleeping pattern and reduce your risk from the serious health issues associated with undiagnosed sleep apnea. A SleepQuest Sleep Care Specialist is available to discuss sleep apnea testing and treatment.