How Do Sleep Trackers Work?

In a perfect world, we would all get the necessary 8 hours of uninterrupted sleep each night and wake up each morning feeling refreshed and rejuvenated. 

In the real world, many of us suffer from a mild, or perhaps more severe, case of sleep deprivation (AKA not enough sleep).

One way to determine if you’re lacking in the snooze department is to begin tracking your sleep habits. This can be easily done by investing in a reliable sleep tracker.

Sounds good, but… how do sleep trackers actually work?

The first step in understanding how sleep trackers work is to know just what these trackers are actually tracking.

What Do Sleep Trackers Monitor?

While no two sleep trackers are exactly the same, they all share two common features: they monitor whether you are asleep or awake and they track how much time you spend sleeping

The ability to track both the quality and duration of sleep you receive is extremely important because it will help determine whether you are a restless or restful sleeper. 

Other aspects of sleep that can be measured through these tracking devices include:

  • Time spent in each stage of sleep (REM vs non-REM sleep)
  • Quality of your sleep environment (light or temperature of your bedroom)
  • Lifestyle factors that may be affecting your sleep (heart rate, food consumption, stress levels)

How Do Sleep Trackers Measure These Factors?

Body Movement

The number one way sleep trackers are able to measure the amount of time you spend asleep is by tracking your body movements. 

Because we are typically more still when sleeping than when awake, body movements are a great indicator of overall sleep duration and quality.

Wearable sleep trackers are able to measure body movement through built-in sensors, a method called actigraphy. Non-wearable sleep trackers rely on other methods such as echolocation and motion sensors.


The presence or absence of noise can be a major indicator to whether you are asleep or awake at any given moment.

Using an internal microphone, sleep trackers are able to record any noises that may be interfering with your ability to sleep peacefully through the night.

These noises can come from within your body, like snoring or sleep apnea-related breathing irregularities (gasping or choking sounds), or from devices in your bedroom such as TVs or smartphones.

Heart Rate

Another method that sleep trackers use to determine the quality and duration of your sleep is by monitoring your heart rate throughout the night. 

Because your heart rate remains steady throughout non-REM sleep and spikes during REM sleep, this is also one method of determining how long you’re in each stage of sleep.

Wearable sleep trackers use built-in heart rate monitors (HRM) to measure your pulse, while non-wearable trackers rely on ballistocardiography (BCG) to evaluate heart rate.


The temperature of your sleeping environment plays a major role in the overall quality of sleep you get. 

Many sleep trackers include a thermostat feature which is able to determine the temperature of your bedroom throughout the night and how it may be affecting your sleep.

Some can even connect with your smart home devices to regulate your room temperature based on your personal sleep data.

Blood Oxygen Levels

The latest and greatest sleep trackers on the market are able to monitor your blood oxygen levels using a SpO2 sensor.

This technology can help you determine if you suffer from sleep apnea or other breathing disorders that may interrupt your sleep. 

While variations in your blood oxygen levels are often an indicator that sleep apnea is present, the only way to be 100% sure is to undergo a professional sleep study.

Personal Sleep Tracking vs Professional Sleep Study

Investing in a reliable sleep tracker is a great way to learn the basics of your sleeping habits, but it won’t always tell you everything you need to know.

The one true way to learn ins and outs of your overall sleep health is to take part in a professional sleep study, otherwise known as polysomnography (PSG).

During a polysomnogram, sleep specialists are able to measure additional sleep factors such as eye movement through electrooculography (EOG).

Most importantly, professional sleep studies monitor your brain waves through electroencephalography (EEG) to determine the accurate amount of time you spend in each sleep stage.

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