Fitness Trackers

Apple Watch Heart Rate Below 40 When Sleeping

Discovering your Apple Watch displaying a heart rate below 40 while you’re peacefully asleep can be alarming.

This unexpected problem raises concerns about potential underlying heart conditions, making you question your health and the accuracy of your device.

Understanding the reasons behind this anomaly becomes crucial for your peace of mind and well-being

Apple Watch Heart Rate Below 40 When Sleeping

When it comes to monitoring heart rate during sleep, the Apple Watch proves to be an invaluable tool. With its ECG reading capabilities, it can detect low heart rates and serve as an early indicator of potential problems. If an individual consistently exhibits a heart rate below 40 bpm while sleeping, it is essential to consult with a doctor or heart rate specialist. Such a low heart rate could be a cause for concern as it may be a symptom of underlying heart problems or an indication of high heart rates during other periods. While a low heart rate during sleep can be common among athletes who are in great physical shape, it is important not to dismiss it without proper medical advice.

During sleep, the heart naturally slows down and pumps blood at a relaxed pace. However, consistently low heart rates during sleep may warrant further investigation, especially if an individual is not an athlete in great physical shape. It is crucial to rule out any potential heart conditions or medication-related issues that could be contributing to the low heart rate. Factors such as electrolyte imbalance, obstructive sleep apnea, or the use of certain drugs or medications can affect heart rate and should be considered.

The Apple Watch’s ability to measure heart rate and provide ECG readings can serve as a valuable tool in identifying potential problems. It can act as an alarm, notifying users of any unusually low heart rates during sleep. This feature can be particularly useful for individuals who are concerned about their heart health or have a history of heart issues. By setting appropriate notification settings and linking the Apple Watch to their medical profile, users can receive timely alerts regarding any potentially problematic heart rate readings, even while asleep.

It is important to note that a low heart rate during sleep does not automatically indicate a problem. It is normal for heart rates to vary based on individual factors such as age, weight, and overall health. Athletes and physically fit individuals often exhibit lower resting heart rates due to their cardiovascular conditioning. However, if a consistently low heart rate is observed without a reasonable explanation, it is advisable to consult a medical professional to assess any potential underlying issues.


Apple Watch Random Low Heart rate

As an expert in Apple Watch, I can provide insights on the topic of random low heart rate readings. The Apple Watch Series 7 is a reputable brand that has become a popular diagnostic tool for cardiologists and doctors alike, as it consistently provides accurate heart rate and blood oxygen level measurements with its infrared sensors and green LEDs. Additionally, it offers peace of mind to those who are pacemaker dependent or have heart-related issues, as it serves as a portable monitor that can track heart block and act as an early warning sign for any adverse health events.

However, users have reported issues with the Apple Watch’s heart rate readings, specifically low heart rates below 40 when sleeping, which can be a cause for concern. While it is normal for heart rates to fluctuate throughout the day, consistently low readings while sitting or sleeping can be weird and make users curious about their heart health. In such cases, it is recommended to consult a cardiologist or medical professional for a workup and conditioning program.

Another concern raised by users is the watch’s validity in comparison to other medical certified monitoring equipment, such as SPO2 devices, Zio patch heart monitors, and Holter monitors. While the Apple Watch can provide accurate readings, its range is limited and may not capture unusual low valleys or high spikes in heart rates. The latest release of the watchOS 8 promises consistency of monitoring, and the accuracy of readings has been improved.

Some users have also reported abnormal heart rates or odd numbers while using the Apple Watch to monitor their heart health. While the watch serves as a convenient diagnostic tool, it is important to take these readings with a grain of salt, especially if they are concerning or dizzying. It is recommended to get a perspective from a doctor or medical professional and not rely solely on the watch’s readings.

In terms of functionality, the Apple Watch has been compared to other heart rate monitoring devices such as the Scosche Rhythm+ and MotiFit. While the infrared sensors and green LEDs provide precise measurements, users with hairy arms or tattoos may experience aberrant readings. Additionally, during exercise or interval workouts, the watch may temporarily show low readings or spikes, making it important to reliably and systematically monitor heart rate during workouts.

Is 40 bpm too low when sleeping?

A heart rate of 40 beats per minute (bpm) while sleeping can be considered normal for certain individuals, such as young, healthy adults or those who are very fit. Bradycardia refers to a slower than normal heart rate, and if you fall within these categories, a heart rate of 40 bpm while sleeping should not be a cause for concern. However, it’s important to note that individual circumstances can vary, and it’s always advisable to consult with a medical professional if you have any specific concerns about your heart rate or overall health.

What is the lowest heart rate Apple Watch can detect?

The lowest heart rate that an Apple Watch can detect is set at a threshold of 40 bpm. If the heart rate dips below this number during a 10-minute resting period, the Apple Watch will alert the user. However, it is possible to change this threshold if it is considered too low, especially for individuals who are not professional athletes.

How low is too low for heart rate while sleeping?

According to the provided information, it is mentioned that during deep sleep, a person’s heart rate may fall below 60 BPM. However, it is also stated that physically active adults, including athletes, often have a resting heart rate that is slower than 60 BPM. Therefore, while sleeping, a heart rate below 60 BPM may not necessarily be considered too low, especially for individuals who are physically active or athletes. The specific threshold for what is considered too low for heart rate while sleeping can vary depending on various factors and individual circumstances. It is advisable to consult with a healthcare professional for a more accurate assessment of what might be considered too low for an individual’s heart rate during sleep.


In conclusion, the Apple Watch offers valuable insights into heart rate patterns, including during sleep. It can help users identify and address any unusual or concerning heart rate readings, serving as an additional resource to bring potential heart problems to light. By regularly monitoring heart rate and seeking medical advice when necessary, individuals can proactively manage their heart health and make informed decisions about their well-being.

Robert Smith
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Robert Smith

Robert Smith is a technology lover and loves to write about laptops, monitors, printers, tablets, Apple products and anything that's related to computers and games. He is passionate enough that he maintains this blog regarding tech updates on a daily basis.