Your Heart: An Impressive Muscle
The heart is a remarkable muscle. It never stops beating from the day you are born to your final moment. According to some estimates, that means your heart muscle will beat over four billion times across your lifetime.
But while it never stops, your heart does slow down. And that, in part, is what sleep is all about. During sleep, all of your body’s processes save energy — and your heart adopts a slower sleeping heart rate to do just that.
So, what is a normal sleeping heart rate? And when should you be worried? Let’s take a look.
What is the Normal Heart Rate for Adults?
During the day, when you’re awake, your heart beats continuously. But the speed at which it beats varies depending on what you’re doing — and, importantly, who you are. That means while we can talk about a normal heart rate, it is only an average. In fact, a heart rate range is much more appropriate.
Let’s start with your resting heart rate:
- Resting heart rate. This is when you are sitting still, quietly, and peacefully. Typically, it’s between 60 and 100 beats per minute (BPM).
What is a good resting heart rate? Most doctors suggest that the lower, the better. Generally, this is a sign of good health, as it puts you at a lower risk of medical conditions such as cardiovascular disease.
However, you won’t always have a resting heart rate. When you’re active, your heart rate goes up. To work out your target heart rate during exercise, you need to do a little calculation:
Calculating Active Heart Rate
According to scientists, your target heart rate during moderate physical activity should be between 64% and 76% of your maximum heart rate:
- Maximum heart rate. This is the maximum speed your heart should be beating. It’s related to your age. Doctors use a simple formula to work this out:
220 – [your age] = maximum heart rate
So, if you are 40, your maximum heart rate will be 180. It is worth checking in with a doctor if your heart rate regularly goes above this.
- Target heart rate. During moderate exercise, you should aim for 64% to 76% of 180, equal to 113.4 to 136.8 BPM.
Aim for 77% to 93% of your maximum heart rate during intense activity. For 40-year-olds, that means 138.6 to 167.4 BPM.
But what about when you are sleeping?
Your Sleeping Heart Rate
Your sleeping heart rate is simply the rate at which your heart beats while you sleep. If you don’t have a device that can track your nocturnal heart rate, this can sometimes be difficult to calculate.
Typically, your heart rate drops by about 20% to 30% of your normal resting heart rate while you sleep. So, if your resting heart rate is 80, you can expect your sleeping rate to be between 56 and 64.
However, just as during the day your heart rate fluctuates, your sleeping heart rate changes during the night too. It is during deep sleep that you can expect your heart rate to reach this level, but there are other stages of sleep where you’ll have a different heart rate:
- Light sleep: During light sleep, your heart rate will not be as low as during deep sleep, studies show.
- REM sleep: During rapid eye movement sleep, you experience a high heart rate variability, and studies show that it can change even more than when you are awake. That’s because REM is when you’re dreaming, and the qualities of your dreams affect your heart rate.
So, all sleep is not created equal. There are a lot of changes going on, and these affect your heart rate too.
Factors Affecting Your Heart Rate
So, what affects the speed of your heart? That’s down to your overall health:
- Activity levels: Trained athletes who do lots of exercise tend to have lower heart rates. The more exercise you do, the lower your heart rate will be.
- Cardiovascular health: High blood pressure and heart disease can contribute to a faster heart rate.
- Obesity: Your body size contributes to a faster heart, and this is particularly true if you are obese.
- Caffeine and tobacco: Both have been found to increase your heart rate, even during sleep.
- Bradycardia: The name for exceptionally slow heart rates. According to the American Heart Association, bradycardia is diagnosed in people who have a heart rate lower than 60 BPM.
- Weather: It might sound surprising, but in hot weather or high humidity, your heart rate will go up. This is perfectly normal.
- Emotions: Stress and anxiety can both have an impact on causing a fast heart rate, and studies have shown that’s even when you sleep.
- Some medications, such as those for thyroid problems and high blood pressure (like beta-blockers), can affect your heart rate.
When to Worry
Having a too high resting or sleeping heart rate is normally not a problem. But it can be a sign of poor heart health.
If you have a high resting heart rate, alongside any of the following symptoms, it is worth talking to a doctor:
- Chest pain
- Arrhythmia. Similarly, when your heart beats irregularly, this is known as heart arrhythmia. Your heart could be too fast (what’s known as tachycardia) or too slow, or it could be highly variable.
- Shortness of breath
- Heart palpitations.
These symptoms could be a sign that not everything is okay. While every man’s body is different, it could signal an underlying cardiovascular disease, or it could mean that you are at greater risk of heart attack or heart failure.
Alternatively, if your sleeping heart rate is very low, there’s usually no reason to worry. However, if alongside a low heart rate, you regularly experience lightheadedness or a lack of energy during the day, it could suggest that your heart is not pumping enough blood around your body.
In this case, do seek medical advice.
Key Takeaways
Your sleeping heart rate is usually about 20% to 30% lower than your average resting heart rate. If you have a lower resting heart rate, your sleeping heart rate is likely to be lower too.
You don’t usually need to worry if you have a fast heart rate or slow sleeping heart rate. But if this is combined with other symptoms – such as shortness of breath or lightheadedness – it’s worth talking to a doctor.
FAQs
What is a Good Sleeping Heart Rate by Age?
According to the US National Institutes of Health (NIH), your resting heart rate depends on your age. It will look a little like this:
- 1 month old – 70-190
- 1-11 months – 80-160
- 1-2 years – 80-130
- 3-4 years – 80-120
- 5-6 years – 75-115
- 7-9 years – 70-110
- 10+ – 60-100
Significantly, your resting heart rate will stay pretty constant after this. Remember, your sleeping heart rate is 20% to 30% lower than your resting heart rate.
Is a Heart Rate of 40 OK When Sleeping?
A heart rate of 40 is okay when sleeping. It is quite low, but if you are not experiencing any other symptoms – such as low energy or lightheadedness – there maybe no reason to worry. This is particularly true if you live a very active lifestyle.
¹ScienceFocus -Does a human heart have a finite number of beats? – https://www.sciencefocus.com/the-human-body/does-a-human-heart-have-a-finite-number-of-beats/
²P Palatini, S Julius (2004). Elevated heart rate: a major risk factor for cardiovascular disease – https://pubmed.ncbi.nlm.nih.gov/15702618/
³Thomas Penzel, Jan W Kantelhardt, Chung-Chang Lo, Karlheinz Voigt & Claus Vogelmeier (2003). Dynamics of Heart Rate and Sleep Stages in Normals and Patients with Sleep Apnea – https://www.nature.com/articles/1300146
⁴Danguol Žemaityt, Giedrius Varoneckas, Kȩstutis Plauška, JonasKauknas (2002). Components of the heart rhythm power spectrum in wakefulness and individual sleep stages – https://www.sciencedirect.com/science/article/abs/pii/0167876086900061?via%3Dihub
⁵Bradycardia: Slow Heart Rate – https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia/bradycardia–slow-heart-rate
⁶Hall, Martica PhD; Vasko, Raymond PhD; Buysse, Daniel MD; Ombao, Hernando PhD; Chen, Qingxia MS; Cashmere, J. David BS; Kupfer, David MD, and; Thayer, Julian F. PhD (2004). Acute Stress Affects Heart Rate Variability During Sleep –https://journals.lww.com/psychosomaticmedicine/Abstract/2004/01000/Acute_Stress_Affects_Heart_Rate_Variability_During.9.aspx
⁷MedlinePlus -Pulse –https://medlineplus.gov/ency/article/003399.htm
While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.
