The sensation that your heart is racing is just one of the ways people describe heart palpitations. It may also feel like your heart is fluttering, pounding, or skipping a beat.

Waking up with your heart racing can be distressing, but it’s not necessarily a sign of something serious. Palpitations are very common and usually harmless.

There are a number of everyday things that can make you wake up with your heart racing. Sometimes, an underlying condition may be the reason. Read on to learn the causes and what you can do to calm your racing heart.

There are many possible causes of a fast heart rate in the morning. Here’s a look at some common ones and other symptoms to watch out for.

Anxiety

Stress and anxiety trigger the release of stress hormones, which in turn increase your heart rate and blood pressure. The more anxious you feel, the more pronounced your symptoms can be.

If you have depression or anxiety, or are under a lot of stress, you may wake up with a racing heart from time to time.

Other common symptoms of anxiety include:

Drinking alcohol the night before

If you’re waking up with your heart racing after drinking, chances are you’ve had too much.

Drinking alcohol increases your heart rate. The more you drink, the faster your heart beats. A recent study confirmed that binge drinking and long-term heavy alcohol use are associated with different types of cardiac arrhythmia, especially sinus tachycardia.

You may also have other symptoms, such as a headache, muscle aches, nausea, and dizziness. These symptoms should clear up as your hangover subsides.

Sugar

The sugar you consume is absorbed into your bloodstream after passing through your small intestine. Having too much sugar can cause a blood sugar spike. This signals your pancreas to release insulin and convert what it can to energy.

The increase in blood sugar and energy is interpreted by your body as stress, which triggers the release of stress hormones. Along with a racing heart, you may also begin to sweat. Some people also get what’s known as a “sugar headache.”

Processed sugar isn’t the only cause. Refined carbohydrates, such as white bread or pasta, can have the same effect, especially in people with diabetes.

Atrial fibrillation

Atrial fibrillation (AFib) is the most common type of irregular heartbeat. It happens when the heart’s upper chambers beat out of coordination with the lower chambers.

AFib usually causes a fast heart rate, but some people feel a fluttering or thumping in the chest. AFib itself isn’t usually life-threatening. In some cases, it can increase the risk of heart failure and may require treatment.

If you have AFib, you may also experience:

Sleep apnea

Sleep apnea is a sleep disorder in which breathing repeatedly stops and starts.

Obstructive sleep apnea is the most common type. It occurs when your throat muscles relax, causing your airway to narrow or close.

Research shows that sleep apnea increases the risk of irregular heart rate. The sudden drops in your blood oxygen levels raise your blood pressure and strain your cardiovascular system.

Some symptoms of sleep apnea are:

Caffeine

Caffeine is a natural stimulant commonly found in coffee, tea, and cacao plants. It stimulates your brain and central nervous system, which increases alertness. In some people, too much caffeine can increase heart rate and blood pressure and cause anxiety and nervousness.

Consuming a large amount of products containing caffeine, such as coffee, tea, soda, and energy drinks can cause your heart to race. Other side effects of too much caffeine include:

  • feeling jittery
  • irritability
  • trouble sleeping
  • shakiness
  • frequent urination

Diabetes

Diabetes causes high blood glucose levels, which can damage the walls of your arteries and cause a rapid heart rate, high blood pressure, and other heart-related complications. In 2015, researchers also discovered that a rapid heart rate increases the risk of diabetes.

Other symptoms of diabetes include:

  • frequent urination
  • excessive thirst
  • extreme hunger
  • fatigue
  • tingling or numbness in the hands and feet
  • blurred vision

Medications that contain stimulants

Just like caffeine, other stimulants can cause your heart to race. Certain over-the-counter (OTC) and prescription medications can include such stimulants.

These include:

Hypoglycemia (low blood sugar)

Rapid heart rate is just one of the possible effects of low blood sugar on your body. Going a long time without eating can cause low blood sugar as well as certain conditions, like:

  • diabetes
  • liver disease
  • kidney disease
  • adrenal gland disorders
  • heavy alcohol use

Other symptoms of low blood sugar include:

Nightmares or night terrors

Nightmares and night terrors can cause you to wake up with a racing heart. Nightmares are disturbing dreams that can wake you up. Night terrors are a type of sleep disorder in which a person awakens partially in a state of terror.

If you wake up after an upsetting dream or night terror with your heart racing, your heart rate should slow as you calm down.

Cold or fever

Any drastic change in your body temperature can cause changes in your heart rate.

Your body reacts to a change in temperature by triggering processes to try to regulate your body temperature. This includes expanding and constricting your skin’s blood vessels to help keep heat in or carry it to your skin’s surface, causing muscle contractions and shivering.

Your heart rate can increase as a result of your body working harder to maintain its normal temperature. For many people, this is around 98.6°F (37°C).

Overactive thyroid

Also called hyperthyroidism, this condition occurs when your thyroid gland produces too much of the hormone thyroxine. It can accelerate your metabolism and cause a rapid or irregular heartbeat as well as unintentional weight loss.

Other symptoms you may notice include:

Lack of sleep

Along with a number of other negative effects on your body, there’s evidence that sleep deprivation can also increase your heart rate.

Aim to sleep seven to nine hours every night. Not getting enough sleep can lead to clumsiness and a higher risk of accidents. It also causes daytime drowsiness, concentration problems, and headaches.

Anemia

Anemia occurs when there are too few healthy red blood cells in your body to carry the amount of oxygen your body’s organs and tissues need to work properly.

Anemia can occur when your body doesn’t make enough or destroys red blood cells. People with heavy periods have a higher risk for anemia, too.

Along with abnormal heart rhythms, anemia can also cause:

  • fatigue
  • weakness
  • shortness of breath
  • headaches

Dehydration

Dehydration is the result of your body losing more fluid than it takes in. When your body loses too much water, your cells and organs aren’t able to function properly. Dehydration can be mild or severe. If left untreated, it can cause serious complications.

Common symptoms of mild dehydration are:

  • dry mouth
  • increased thirst
  • decreased urination
  • headache

Symptoms of severe dehydration include:

Periods, pregnancy, and menopause

Fluctuating hormone levels related to menstruation, pregnancy, and menopause can trigger the feelings of a racing heart.

During the menstrual cycle, estrogen and progesterone levels rise and fall. This has been linked to episodes of a faster-than-normal heart rate called supraventricular tachycardia.

Heart palpitations during pregnancy are caused by the increased amount of blood in the body, which can cause your heart to beat 25 percent faster than usual.

In perimenopause and menopause, the decrease in estrogen production is associated with an increase in heart rate. This can cause frequent palpitations and nonthreatening arrhythmias.

Hot flashes can also trigger palpitations in menopause and cause your heart rate to increase by 8 to 16 beats.

Here are some other symptoms that can accompany waking up with a racing heart and what they could mean.

Waking up with a racing heart and shaking

Waking up with a racing heart and shaking may be caused by:

  • consuming too much caffeine
  • taking medications that contain stimulants
  • diabetes
  • hyperthyroidism
  • being cold
  • fever
  • a nightmare or night terror

Waking up with a racing heart and shortness of breath

Waking up with a racing heart and shortness of breath may be caused by:

  • anemia
  • AFib
  • sleep apnea
  • anxiety

Having a racing heart, chest pain, and dizziness

A racing heart, chest pain, and dizziness are warning signs of a heart attack. If you or someone else are experiencing these symptoms, call 911 or your local emergency services right away.

Medical emergency

A heart attack is a medical emergency and needs immediate medical treatment. Go to the nearest emergency room if you experience these symptoms.

Your doctor will begin by asking about your symptoms and performing a physical examination. They’ll listen to your heart and check for signs of conditions that can cause a racing heart, such as an enlarged thyroid.

Your doctor may also order one or more of the following tests:

A racing heart that’s an infrequent occurrence and only lasts a few seconds doesn’t usually need to be evaluated. See a doctor if you have a history of heart disease or your palpitations worsen.

If your racing heart is accompanied by shortness of breath, dizziness, or chest pain, seek emergency medical help or call 911.

Waking up with a racing heart isn’t typically serious and doesn’t require treatment if it only happens occasionally or lasts just a few seconds.

But if your symptoms are interfering with your daily activities or causing you distress, see a doctor. They can rule out an underlying medical condition and work with you to get relief.