How does Garmin measure deep sleep?

In this guide, we will talk about how Garmin measures deep sleep, advanced sleep monitoring, a list of some of the compatible devices with advanced sleep monitoring, how accurate Garmin is when measuring sleep and some additional things to consider.

How does Garmin measure deep sleep?

If you would like to know how Garmin measures deep sleep, here we have the answer. Garmin uses Advanced Sleep Monitoring and this feature works employing an optical heart rate sensor on the device to measure Heart Rate Variability. Simply put, it is the time measured between each heartbeat and when combined with the accelerometer readings, it allows you to determine when you have fallen asleep when you wake up and the stage you are in. 

But, what is the importance of measuring deep sleep? This stage is regarded as one of the most important stages of the sleep cycle since it helps the body recover and boosts your immune system, among other things. During deep sleep, your breathing, heartbeat, brain activity and body temperature reach their lowest levels. Moreover, your muscles are extremely relaxed and it becomes difficult to wake you up.

Garmin has seen the importance to measure deep sleep so it has introduced sleep cycles and levels when sleeping:

  • Light sleep: refers to the stage where eye movements and muscle activity begin to slow down as the body prepares for deep sleep.
  • Deep sleep: refers to the stage where eye and muscle movements stop entirely. Your heart rate and breathing slow down. This stage is also known as the healing stage, where your body can recover, build bone and muscle, important hormones are released and boost your immune system.
  • REM sleep: this stage is also known as the dream stage, where your brain activity is almost as active as when you are awake. REM sleep is very important to consolidate memories and learning. 

Advanced Sleep Monitoring

New Garmin watches have a feature called Advanced Sleep Monitoring or ASM. With ASM, users can have the ability to track their sleep in Garmin Connect when they are wearing the device at night when they are sleeping. ASM is available mainly on watches that have an optical heart rate sensor. 

You may wonder, How does Advance sleep monitoring work? Well, it uses an optical heart rate sensor on the device as we have mentioned, to measure HRV. Here are some of the basic requirements according to Garmin Support:

  • Having a compatible device with advanced sleep monitoring.
  • Updating the Garmin Connect app and installing any available updates.
  • The device must be worn at least 2 hours before going to bed.
  • The optical heart rate sensor must be enabled while sleeping.

List of compatible devices

Here is a list of some of the devices compatible with advance sleep monitoring:

  • Approach S62
  • D2 Charlie
  • D2 Delta series
  • Descent Mk1
  • Descent Mk2 series
  • Fenix 5 series
  • Fenix 5 Plus series
  • Fenix 6 series
  • Legacy Saga Series – Darth Vader
  • Legacy Saga Series – Rey
  • MARQ Collection
  • Quatix 5 series
  • Quatix 6
  • Tactix Charlie
  • Tactix Delta
  • Venu
  • Venu Sq series
  • Vivoactive 3 series
  • Vivoactive 4 / 4S
  • Vivomove HR
  • Vivomove 3
  • Vivomove 3S
  • Vivomove Style

 Is Garmin accurate when measuring sleep?

As indicated by Garmin Support, to get the most accurate sleep data:

  • Wear the device at least 2 hours before bedtime and keep it on while you are sleeping.
  • Make sure the device’s heart rate monitor is on, and the device fits you comfortably, not too tight or loose.
  • If you own more than one activity tracker, set the device with an advanced sleep monitor as your ‘Preferred Activity Tracker’. 
  • Under the Garmin Connect User setting, make sure there is a valid birth date. 
  • Make sure that your average sleep and wake times are set correctly. 

Previous measurements 

When we talk about sleep monitoring we may consider only the latest technology. However, many devices such as smartphones, promise to track our sleep with the use of certain apps, such devices only use movement and/or heart rate to analyze your sleep. This was also the case for some Garmin devices but with the update, the new devices use HRV to measure your sleep.

However, as recommended by Garmin, “Make sure your compatible watch is set as your preferred activity tracker. For the best reading, make sure your watch is on securely — but comfortably — a few hours before bed and the whole time you’re asleep”.

What Garmin sleep reveals

We would all like to get the best sleep at night, not having to wake up tired and/or feeling sleepy throughout our day. Many people, including myself, get very upset and cranky after not having enough sleep. Our mood and health get affected when we are not able to get enough sleep. 

After a good night’s sleep or in some cases a short (and not so good) night’s sleep, you can see the breakdown of the time you have spent in the different sleep stages and also the duration of any periods when you were awake.  However, the sleep stats will not be displayed on the watch itself but the Garmin Connect app or web tools.

Moreover, the app allows you to add a widget to get your most recent sleep time displayed on your ‘My Day’ screen. Also, you can get the breakdown by hitting ‘More’ and then tap into your health stats. If you see the timeline presented and you spot an error, you can manually edit the information in the Garmin Connect app and the web tools. 

But there is an additional measure you will see called Pulse Ox. Well, since this measure will be recorded as you are sleeping, you will see a movement line showing the level of oxygen in your blood, also known as SpO2. The normal range is between 94 to 100% range. If you get a score particularly below 90% it may be a sign of health issues (i.e. sleep apnea). 

Why is this blog about How does Garmin measure deep sleep important?

As we have discussed on how Garmin measures deep sleep, it is pretty similar to some other devices by brands such as Samsung or Huawei. However, this doesn’t mean it makes sleep tracking less interesting. We find fascinating how this kind of technology can record sleep cycle stages with such accuracy. The only thing we would have to say is a feature left to be improved is that Garmin won’t consider naps when recording the data. 

Finally, we have mentioned how important are all of the sleep cycle stages but we made special emphasis on deep sleep because a lot of things happen during this stage without even noticing. This is why tracking your sleep may allow you to improve the quality of your sleep and also your overall health.

Please feel free to leave any comments or thoughts about the content of this article!

Frequently Asked Questions (FAQs) about How does Garmin measure deep sleep

Is Garmin deep sleep accurate?

According to studies performed by Garmin showed that the classifier predicts deep, light and REM sleep stages at roughly 69& accuracy rate. Wake is slightly more accurate at 73% and the most common misclassifications are classifying true deep sleep as light sleep and classifying true REM sleep as light sleep. 

How much deep sleep do you need Garmin?

It is said that we need on average 1 to 2 hours of deep sleep per 8 hours of nightly sleep. Scientists agree that sleep is essential and while stages 1 to 4 and REM sleep are very important, deep sleep is believed to be extremely essential. 

How is deep sleep measured?

Sleep researchers usually measure deep sleep with the use of polysomnography or PSG, normally in a lab setting. This is known to be the ‘Gold Standard’ for measuring sleep and researchers seem to agree that PSG is the best way to measure sleep. However, if we refer to a wearable device such as a smartwatch, it usually employs the heart rate optical sensor to detect changes in heart rate to determine sleep cycle stages.

Is Garmin or Fitbit better?

Garmin offers a greater emphasis on VO2 max and heart rate zones, making it highly efficient for training purposes and the preferred option for athletes. In contrast, if you are looking for a lifestyle tracker, then the Fitbit would be a better choice. 

How can I get more deep sleep and less light sleep?

If you would like to get more deep sleep and less light sleep at night, here are some recommendations:

Try to keep your diet sleep-friendly, meaning that a low carbohydrate diet helps promote and increase deep sleep time when compared to having a mixed diet.
Try Pink Noise.
Meditation before going to bed.
Exercise regularly.
Listen to relaxing music.