10 Interesting Facts About Sleep Cycles and Your Heart Rate

Sleep. We all need it, but many Americans don’t get the sleep they need to stay in peak health. That’s a problem because sleep is an essential part of life and how the human body regenerates, recovers, and stays healthy. 

To fix the problem, several manufacturers have created devices that monitor a person’s sleep cycle, showing them how much sleep (and what type of sleep) they get every night. These devices rely on several factors to do this, one of which is the most important; your heart rate. Indeed, these biohacking devices wouldn’t be of much use without the data they collect about heart rate. 

If you’re not sleeping well or so badly that it’s affecting your health and wellness, today’s article is for you. (Or a family member or friend who has sleeping challenges.) In it, we’ll take a closer look at how heart rate and the sleep cycle are interconnected and how to make sure you get the restful sleep you need. So prop your eyes open with a couple of toothpicks, grab a cuppa’ joe and read on! Enjoy.

1- Resting Heart Rate (RHR) Tells Us a Lot About How We’re Sleeping

Like your fingerprint, your body’s resting heart rate (RHR) is unique. That’s why biohacking devices like Oura record your RHR when you sleep. It’s also why, if you’re looking for clues about your sleep cycle, you don’t want to compare yours to anyone else’s because everyone is different. It’s best to compare your RHR to your own baseline, which is your regular heartbeat during waking hours.  

2- Normal Heart Rate Varies from Person to Person

Just as everyone’s RHR is different, the average waking heart rate differs between individuals. The average ranges from 40 beats per minute (BPM) to upwards of 100 BPM, a rather large difference, no doubt. What’s truly interesting is that your heart rate can also vary during the day based on a variety of factors, including:

  • Your hydration level (how much water is in your body)
  • Your physical activity level 
  • The elevation where you’re located
  • Your body’s temperature

3- 3 Factors That Are Most Important When Looking at RHR

To get a baseline heart rate, three factors need to be addressed. Knowing them will allow you to use any device properly, as well as help modify your sleeping patterns and other habits.  They include:

  1. Your lowest RHR during the night
  2. Your ending RHR just before you wake up in the morning
  3. Your RHR trend. For example, does your RHR go up at night, go down or stay relatively level?

4- Your RHR Changes During the Night as Your Sleep Changes

As we sleep, our RHR changes when the type of sleep we’re getting changes. That’s good because it means biohacking devices like the Fitbit can use those changes to tell you how much of the three different types of sleep you’re getting, including:

  1. Light sleep
  2. Deep sleep
  3. REM (rapid eye movement) Sleep

Heart rate biohacking devices show when, for example, you transitioned from one sleep cycle to another, as well as any time during the night that you were restless or woke up for a few minutes. Interestingly, no matter how well (or poorly) you sleep, most of us transition from one sleep cycle to another every 70 to 90 seconds.


5- Sleep Apnea Can Cause Your RHR To Spike During the Night

One relatively serious problem that a sleep biohacking device can tell you is whether you have sleep apnea or not. Sleep apnea is when your regular breathing is either reduced or, in some cases, completely stops while you sleep. Of course, your body needs oxygen to survive and will do what it can to keep breathing, but during periods of sleep apnea, your heart rate will spike.


Luckily, if you have sleep apnea, your brain will recognize that something is going wrong and, if you don’t get the oxygen you need relatively quickly, it will wake you up. That will then “kickstart” your normal breathing once again but in the process will also, unfortunately, wake you from sleeping, which is highly unhealthy if it occurs too often.

6- If You’re Interrupted 5 Times Or More By Apnea Within an Hour, You have Sleep Apnea 

As we mentioned, sleep apnea is when, for some reason, you don’t get the oxygen you need while sleeping, usually caused by some sort of airway blockage. A heart rate tracking device will record these apneas even if you don’t remember them (which many don’t). If you see that t’s happening more than five times per hour, you’ve likely got obstructive sleep apnea and should see a health specialist to find a solution.

7- Sleep Apnea Can Cause a Cortisol Spike To Force Your Body to Breathe In Oxygen

To make sure you don’t die from lack of oxygen, your body sends out a quick blast of the hormone cortisol. Known as the ‘stress hormone,’ cortisol does a great job of waking you and forcing your body to take a deep gulp of air. The problem is that it also causes your heart rate to spike and your sleep to be interrupted. Also, it can cause a lot of stress on your heart in the long-term, which is never a good thing for your overall wellness.

8- Sleeping On Your Side Is Best

If you have sleep apnea (and even if you don’t), the best position for sleeping is on your side. That way, your body gets the oxygen it needs throughout the night, and your sleep isn’t interrupted (or at least is interrupted less).

9- Your Neck Size Is An Important Factor for Good Sleep

This is truly interesting. If you’re overweight, it can cause your neck size to increase, leading to sleep apnea and other health problems. Rather than merely losing weight, targeting an optimal neck size is best. For men, that would be about 17 inches in circumference. For women, 15 inches in circumference is best.

10- The Best Ways To Improve Your Sleep Cycles

Here are a few of the best ways to change your sleep cycles and start sleeping better:

  • Sleep in a very dark room.
  • Practice meditating, yoga, stretching, or journaling before bedtime.
  • Get at least 30 minutes of exercise or aerobic activity five days a week.
  • Make sure your bedroom is quiet or that you use white noise to cover any obstructive noises.
  • Keep your bedroom cool at night.
  • Don’t eat any food from 2 to 3 hours before sleeping.
  • Try to keep a regular sleep schedule.
  • Consider intermittent fasting. You can read more about that here.

Last Words

Sleep is one of the most important activities the human body performs every day. It refreshes the body and allows it to heal, a vital function that’s more important than most realize. (But not you, dear reader, because you’re here educating yourself!) Using a biohacking device is an excellent way to see if you’re sleeping well or not. 

That being said, biohacking sleep devices don’t help you sleep better but only give you info and data about your sleep cycles and heart rate. To change your sleep, you need to change habits like eating close to bedtime, sleep position, etc. Only then will your heart rate and sleep cycle sync-up to get you the good night’s rest your body desperately needs.

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