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What causes a racing heart when falling asleep?

This Premium Q&A, reviewed and published, features a real conversation between an iCliniq user and a physician.

Patient's Query

Hello doctor,

A few times when I am falling asleep, I feel like my heart is racing. I took an ECG (electrocardiogram) on my watch and would like to know if it is normal. I had COVID-19 two weeks ago. A couple of times when falling asleep, I felt like my heart was speeding up. I messaged my cardiologist.

He thinks it is benign, but I took this ECG when it was happening. I have a previous history of anxiety and depression.

Please help.

Thank you.

Answered by Dr. Wajahat

Hello,

Welcome to icliniq.com.

I read your query and can understand your concern.

The provided ECG (electrocardiogram) rhythm strip demonstrates a normal sinus rhythm with a heart rate approximating 70 beats per minute. All measured intervals fall within typical parameters, and the available data does not reveal any indications of arrhythmia (irregular or rapid heart rhythm) or myocardial ischemia. Experiencing a rapid or fluttering heartbeat is often referred to as palpitations. These sensations can arise from a diverse range of factors, including psychological triggers such as anxiety or stress.

Physiological conditions like anemia (low hemoglobin levels), dehydration, and electrolyte imbalances can also contribute. Furthermore, underlying medical issues such as thyroid disorders and certain cardiac conditions may manifest as palpitations.

Lifestyle factors, including excessive consumption of nicotine or caffeine, the use of specific medications, and insufficient sleep, can also play a role. Interestingly, even seemingly unrelated issues like infections in any part of the body can sometimes trigger these heart sensations.

I hope I have answered your question.

Let me know if I can assist you further.

Thank you.

Patient's Query

Hello doctor,

  1. What about the dip in the S wave?

  2. Why would this only happen while falling asleep?

It feels like a rush of blood to the chest and does not feel like a palpitation.

Please help.

Thank you.

Answered by Dr. Wajahat

Hello,

Welcome back to icliniq.com.

I read your query and can understand your concern.

The S wave in the rhythm strip is a normal variant. There is nothing clinically significant in this ECG (electrocardiogram) strip. Regarding the sensation of a rush of blood to the chest, it is very common to have an increased awareness of internal bodily sensations while falling asleep, as a person is less distracted. We can perceive our heartbeat (called palpitations) or the sensation of blood flow, especially in the chest, neck, or head region. This does not signify anything clinically significant in itself.

Are you experiencing any associated chest pain, shortness of breath on lying down or walking, chest heaviness, or episodes of a fast heart rate or tachycardia?

I hope this answered your question.

Let me know if I can assist you further.

Thank you.

Patient's Query

Hello doctor,

No, I am not. My resting heart rate is always low, in the 60s. Another thing I wanted to ask was this. I hardly ever drink at all. I went out with a friend and had a couple of mimosas and noticed a lot of palpitations that day. I do not have any other symptoms, just palpitations.

Is that normal?

That was the first time I had a drink in a year and a half.

Answered by Dr. Wajahat

Hello,

Welcome back to iclliniq.com.

No, you should not have tachycardia or palpitations with that. If this happens more than once, I would recommend a 12-lead ECG and Holter monitoring for at least 72 hours. This would make many things clear, and we would be able to see why you are having these symptoms.

  1. Have you ever had an echocardiogram? If yes, please share the reports.

  2. Has any laboratory work-up, such as CBC (complete blood count) or any other laboratory tests, been done in the last six months? If yes, please do share.

I hope I have answered your question.

Let me know if I can assist you further.

Thank you.

Patient's Query

I’ve had an echo all normal. Had one 3 years ago. Does that need to be repeated? Also, I was told that palpitations while running are okay. Is that true? I sleep with an iwatch so it’s not low hr, high hr, or afib. 60-80bpm during sleep. Should I still get a holter? I’m assuming this will be answered bc it was in the allotted time
Answered by Dr. Wajahat
Thank you for your reply. If your echocardiogram was normal and there was no evidence of any structural heart disease, then you do not need to repeat your echocardiogram right now. Yes, it is normal to feel palpitations while exercising or running. If the increase in heart rate is adequate and there is no aberrant rhythm while exercising, then it is very reassuring. You should get Holter monitoring done if you have a resting fast heart rate or tachycardia, a very fast heart rate with minimal exertion, any suspicion of an aberrant heart rhythm, skipped beats or premature beats, or any pauses. These are some of the indications for getting Holter monitoring done. Please do not hesitate to contact me if you need to know anything else and I would be happy to answer. I hope this information is helpful. Regards
Answered byDr. Wajahat
Medically reviewed byDr. K. Shobana
Published At June 11, 2025
Reviewed AtJune 24, 2026

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