High Heart Rate While Sleeping: Causes, Sudden Spikes, and When to Worry

If you’ve woken up, checked your smartwatch or sleep tracker and noticed your heart rate climbed much higher than usual during the night, it may worry you. It could have happened once, or maybe you’re starting to see the same pattern over several nights.

Heart rate naturally changes while you sleep. It may rise for short periods because of dreaming, movement or briefly waking up. However, an unusually high heart rate while sleeping can also be related to poor sleep, illness, alcohol, certain medications, sleep apnea or an abnormal heart rhythm.

What matters is not just one number. How long the increase lasts, how often it happens, how different it is from your usual heart rate and whether you have other symptoms can all provide important context.

Is It Normal for Your Heart Rate to Increase While Sleeping?

Your heart rate doesn’t stay at exactly the same number all night.

Heart reate generally slows during deeper, restful stages of sleep. During REM sleep, which is the stage when many vivid dreams occur, the heart rate and blood pressure can become more variable and may temporarily increase. Movement, changing positions and briefly waking can also cause short changes. So one short heart-rate spike is not necessarily abnormal.

It’s more important to look at the overall pattern. A heart rate that stays unusually elevated for a significant part of the night or repeatedly rises well above your normal baseline may deserve more attention.

Your usual sleeping heart rate can also vary based on many different factors.

Causes of a High Heart Rate While Sleeping

An elevated heart rate while sleeping doesn’t point to one specific condition on its own. Some causes are temporary and relatively harmless, while others may require medical evaluation. 

Sleep Apnea

Sleep apnea causes breathing to stop and restart during sleep. When breathing is interrupted, oxygen levels may fall and the body responds as though it is under stress. Stress hormones can increase heart rate and blood pressure, particularly as breathing resumes or the person partially wakes.

Sleep apnea is an important possible cause of heart rate spikes while sleeping, particularly when the increases happen repeatedly throughout the night, and you may have no memory of these episodes the next morning.

Signs of sleep apnea can include:

• Loud or frequent snoring
• Waking up gasping or choking
• Frequent awakenings during the night
• Morning headaches
• Dry mouth when you wake up
• Feeling unusually tired during the day despite spending enough time in bed

A sleep evaluation may help determine whether sleep apnea is the cause of an increased heart rate while sleeping.

Heart Rhythm Problems

An abnormal heart rhythm, or arrhythmia, can cause the heart to beat too quickly, too slowly or irregularly. These episodes can occur at any time, which includes while you are asleep.

Atrial Fibrillation (AFib) is one possible example, but there are several other types of fast heart rhythms, sometimes called tachyarrhythmias.

These episodes may:

• Begin and end suddenly
• Cause a rapid or irregular heart rate
• Last for seconds, minutes or longer
• Occur only occasionally
• Happen without noticeable symptoms

An intermittent rhythm problem may not occur during the few seconds that a routine office ECG records your heartbeat. When necessary, longer-term monitoring such as a Holter monitor or event monitor can record the heart over a longer period.

People with repeated unexplained nighttime heart-rate spikes may therefore need more than a single smartwatch reading to determine what’s really happening.

Alcohol

Alcohol can affect the nervous system, disrupt normal sleep and contribute to dehydration. Heavier alcohol use is also associated with high blood pressure and an increased risk of certain abmormal heart rhythms, including atrial fibrillation.

You may notice that your overnight heart rate is higher after drinking even when your daytime readings seem normal. If the pattern repeatedly occurs after drinking, consider discussing the readings with your healthcare provider.

Stress, Anxiety, Nightmares and Poor Sleep

Your body does not completely shut down its stress response when you fall asleep.

Stress hormones can increase heart rate. Vivid dreams and nightmares may also temporarily activate the body's fight-or-flight response, particularly during REM sleep, when heart rate naturally becomes more varied.

Nighttime readings can also be affected by:

• Going to bed feeling highly stressed
• Anxiety
• Repeated awakenings
• Poor-quality or fragmented sleep
• Nightmares
• Not getting enough sleep overall

Illness, Fever or Infection

Fever, infection and other illnesses place additional demands on the body. A faster pulse can occur with fever and other forms of physical stress.

For example, a temporary increase while you have a fever, stomach illness or respiratory infection has a different context from a sleeping heart rate that suddenly becomes elevated while you otherwise feel completely well.

Dehydration

When the body loses more fluid than it takes in, the heart needs to beat faster to help maintain circulation. A rapid heartbeat can occur with more significant dehydration.

Dehydration may be more likely after:

• Vomiting or diarrhea
• Fever
• Heavy sweating
• Exercise
• Drinking alcohol
• Not drinking enough fluids during the day

Caffeine, Nicotine and Other Stimulants

Stimulants increase activity in the nervous system and can raise heart rate in some people.

Possible contributors include:

• Coffee
• Energy drinks
• Pre-workout products
• Nicotine
• Certain stimulant medications
• Some cold and allergy medicines

Caffeine or another stimulant does not necessarily stop affecting your body when you get into bed, so timing is important. If you’re consuming caffeine later in the day, it’s more likely to cause issues at bedtime.

Excessive caffeine, tobacco products and certain over-the-counter medications are among the factors associated with episodes of rapid heart rate in susceptible people.

Certain Medications

Prescription and over-the-counter medications can sometimes affect heart rate as well.

Examples may include certain:

• Decongestants
• Asthma medications
• Stimulant medications
• Thyroid medications

This does not mean you should stop taking medication because your watch recorded an unusual number.

If your sleeping heart rate changes after starting a medication or changing your dose, talk with the healthcare professional who prescribed it. They can help determine whether the medication could be contributing and whether anything needs to be adjusted.

Why Does My Heart Rate Suddenly Spike While Sleeping?

A single brief heart-rate spike during sleep may not mean much on its own, especially if your heart rate quickly returns to its usual range and you have no other symptoms.

What matters more is whether the spikes are becoming more of a pattern. Repeated or sustained heart-rate increases are worth discussing with a healthcare provider if they:

• Happen frequently or over several nights
• Last longer than a brief moment
• Are becoming progressively higher
• Occur without an obvious explanation
• Appear irregular
• Wake you from sleep
• Occur along with dizziness, shortness of breath, weakness or other symptoms

It can also be helpful to compare these episodes with your usual nighttime heart rate. A sudden increase that is far outside your normal pattern may be more meaningful than a small fluctuation.

If you’re noticing repeated spikes, save the readings or screenshots from your smartwatch or sleep tracker. Looking at several nights of data can give your healthcare provider a clearer picture of what is happening than one isolated reading.

When Your Sleeping Heart Rate Reaches 100 or 120 BPM

Seeing your heart rate reach 100 or 120 beats per minute while you are asleep can be unsettling, especially if your normal nighttime heart rate is much lower.

In adults, doctors generally use the term tachycardia for a resting heart rate above 100 beats per minute. One brief reading over 100 doesn’t automatically mean something is wrong. There is a big difference between your smartwatch recording 120 bpm for a short moment and your heart rate staying unusually high or repeatedly reaching that level throughout the night.

When looking at a high reading, consider:

• How long it lasted
• How often it happens
• How different it is from your usual sleeping heart rate
• Whether you were sick, dehydrated or had been drinking alcohol
• Whether you had any symptoms at the same time

A single breif reading of 120 bpm isn’t automatically a medical emergency. Symptoms can make a high heart rate more concerning. Chest pain, severe shortness of breath, fainting or other serious symptoms require immediate medical attention rather than waiting to see what your smartwatch shows next.

Heart Rate Readings From Smartwatches and Sleep Trackers

Smartwatches, fitness trackers and smart rings can be useful for spotting changes in your heart rate while you sleep. However, these devices are not the same as medical heart monitoring, and an unusual reading is not always accurate.

Readings can sometimes be affected by:

• Movement during sleep
• A loose-fitting device
• Poor skin contact
• The position of the sensor
• Circulation at the measurement site
• Limitations of the device or its software

This is one reason a single unexpected number should not be used to diagnose a heart problem.

If you repeatedly notice unusually high readings, save the data or screenshots from your device to show your healthcare provider. A wearable may help identify that something has changed, but medical testing may be needed to determine the cause.

When to Have a High Sleeping Heart Rate Evaluated

A single abnormal reading may not warrant a trip to the doctor, however it may be worth speaking with a healthcare provider when you notice an ongoing or unexplained pattern, including:

• Repeated elevated nighttime heart-rate readings
• A sleeping heart rate that has gradually increased
• Frequent unexplained spikes
• Irregular heart-rate readings
• Episodes that repeatedly wake you from sleep
• A major change from your usual baseline
• Known heart disease
• A history of abnormal heart rhythms
• Symptoms of possible sleep apnea 
• Persistent daytime tiredness or poor-quality sleep

Depending on your symptoms and medical history, an evaluation may include:

• A review of your symptoms and health history
• A physical examination
• An electrocardiogram (ECG or EKG)
• Blood tests
• Longer-term heart monitoring
• A sleep evaluation when sleep apnea is suspected

A routine ECG records your heart rhythm for a short period of time. If an abnormal rhythm only happens occasionally, longer-term monitoring with a Holter monitor or event monitor may provide more information.

When symptoms such as loud snoring, gasping during sleep, frequent awakenings or daytime tiredness point toward possible sleep apnea, a sleep evaluation may also be recommended.

Emergency Warning Signs of a High Sleeping Heart Rate.

A fast or abnormal heart rate becomes much more concerning when it occurs with symptoms that could indicate a serious heart or neurological problem.

Call 911 or seek emergency medical care if a fast or unusual heart rate occurs along with:

• Chest pain or pressure
• Severe shortness of breath
• Fainting or near-fainting
• Severe dizziness
• Severe weakness
• New confusion
• New weakness or numbness on one side of the body
• Difficulty speaking
• Other possible symptoms of a heart attack or stroke

Do not wait or schedule a routine appointment first if serious symptoms are occurring.

When to See a Doctor in Queens or Brooklyn for a High Sleeping Heart Rate

If your heart rate is repeatedly higher than usual while you sleep, keeps spiking without an obvious explanation or has noticeably changed from your normal pattern, it may be worth speaking with a medical professional.

An outpatient evaluation may be especially worthwhile when the change is recurrent, noticeably different from your normal pattern, or occurs alongside other non-emergency concerns such as irregular readings, poor-quality sleep, loud snoring or gasping, daytime fatigue, or a history of heart rhythm problems.

At Advanced Medical Care, our cardiologists and sleep medicine team help patients throughout Queens and Brooklyn understand what may be behind unusual nighttime heart-rate readings. Because changes during sleep can sometimes be related to heart rhythm, sleep quality or conditions such as sleep apnea, we can look at the bigger picture rather than focusing on one number alone.

If you have questions about a high heart rate while sleeping, repeated nighttime spikes or changes you have noticed on a smartwatch or sleep tracker, please call us at 347-571-9389 (Queens) or 929-552-2973 (Brooklyn) to schedule an appointment, or book online to get started. We are here to help you better understand what your readings may mean and whether further evaluation makes sense.

Frequently Asked Questions

Is it normal for heart rate to spike while sleeping?

Short increases in heart rate can happen during REM sleep, vivid dreams, movement or brief awakenings. A spike may deserve more attention if it happens repeatedly, lasts for longer periods or is very different from your normal nighttime pattern.

What causes heart rate to suddenly increase during sleep?

Possible causes include REM sleep, nightmares, movement, stress, sleep apnea, alcohol, dehydration, fever, stimulants, certain medications, abnormal heart rhythms and occasional inaccurate wearable readings.

Why is my sleeping heart rate higher than my resting heart rate?

Poor-quality sleep, alcohol, illness, stress, late exercise, dehydration, stimulants, certain medications, sleep apnea and abnormal heart rhythms are possible explanations. A consistent change from your normal pattern may be worth discussing with your healthcare provider.

Is a sleeping heart rate over 100 dangerous?

A heart rate above 100 beats per minute at rest is considered tachycardia in adults, but one brief wearable reading does not tell you why the increase occurred. Repeated or sustained readings, especially when accompanied by symptoms, deserve more attention.

Can sleep apnea cause a high heart rate at night?

Yes. Sleep apnea repeatedly interrupts breathing during sleep. As oxygen levels fall and breathing resumes, the body's stress response can temporarily increase heart rate and blood pressure.

Can alcohol raise your sleeping heart rate?

Yes. Alcohol can affect the nervous system, disrupt sleep, contribute to dehydration and increase heart rate in some people. Some people notice that their sleeping heart rate is higher on nights when they drink alcohol.

Should I worry if my smartwatch shows a high heart rate while sleeping?

One unusual reading does not necessarily mean something's wrong. Pay more attention to whether the increase keeps happening, lasts for longer periods, is far outside your usual pattern or occurs with symptoms.