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How Can Fitness Tracker Help Your Sleep

Sleep is arguably one of the most important contributors to your overall health, albeit the one least understood. People have found it easier to establish direct links between exercise and diet control with health oversleep, mostly in part due to a lack of understanding of just how sleep contributes towards health.

Many wrists these days adorn fitness trackers on them and the fact that they have sleep trackers on them is usually an incidental finding. Commercial fitness bands have pedometers, heart rate monitors, blood pressure measuring, and even oxygen saturation levels. All of this and sleep trackers.

However, the question isn’t whether fitness trackers have sleep trackers or not, it’s over the efficacy of these trackers and the parameters they measure. Also, are these parameters sufficient enough to determine overall health?

How Does a Fitness Tracker Measure Sleep?

Fitness trackers like Koretrak (read KoreTrak review here: https://dis-dot-dat.net/koretrak-review/) have accelerometers installed in them that measure the wearer’s shift in motion. The accelerometers are what measure sleep. The question is, how?

Stillness is usually equated with sleep, while motion is attributed to wakefulness or activity. However, this theory is open to debate because of the two main types of sleep; Rapid Eye Movement (REM) and Non-Rapid Eye Movement (NREM).

Sleep stages correlate with brain waves – something a tracker does not have the capacity to measure. It, therefore, measures the next best thing (or things):

  1. Body Movement
  2. Heart Rate

This information is thereafter tracked into an algorithm whereby the device interprets what could be possibly happening in the brain. The intricate nature of this device is designed specifically to be able to differentiate between REM and NREM (the significance of which will be explained below).

Non-Rapid Eye Movement Sleep

NREM sleep is further divided into three stages; N1, N2, and N3. In total, NREM sleep contributes to being over 75% of the total sleep a person has at night. N1 is the stage between sleep and wakefulness where a person is dozing off, N2 is deep sleep or drowsiness when and contributes to 50% of overall sleep, lastly, N3 is where the transition occurs from NREM to REM and lasts for about 40 minutes.

  • NREM is mediated by ATP recovery.
  • A body can not recover from a lack of NREM sleep.
  • NREM can also be referred to as ‘deep’ sleep.

Rapid Eye Movement Sleep

REM is acetylcholine mediated sleep or ‘light’ sleep as it’s often referred to as. This sleep usually proceeds after NREM sleep and lasts for roughly 90 minutes or so. REM is associated with having dreams and a general feeling of wakefulness of sorts. Why do we have dreams during REM? No one’s entirely sure.

  • REM is acetylcholine mediated.
  • A body can recover from a lack of REM sleep.
  • REM can also be referred to as ‘light’ sleep.

Fitness and Sleep Tracker

Having had understood the mechanism with which a fitness tracker measures and keeps track of sleep, the limitations of one are pretty obvious:

  • REM sleep is often misrepresented as wakefulness.
  • Naps are rarely measured in sleeping time.
  • A tracker can’t accurately differentiate between NREM and REM.

However, this isn’t to say that every fitness tracker with a sleep monitor is inaccurate, or even that fitness trackers are 100% inaccurate. There are trackers approved by the FDA which have close to 100% accuracy and several leading sleep medicine specialists are working on bettering commercially branded sleep trackers.

Interpreting Sleep Metrics

A study2 found that sleep monitoring via fitness bands provided close to accurate data on the following parameters:

  • Duration of deep sleep
  • Environmental factors
  • Sleep quality
  • Comparison variables

Interpreting this data obtained from a fitness sleep tracker bracelet can actually help live a healthier and more active lifestyle. Sleep trackers in fitness bracelets can also help in improving the quality of your sleep to avoid problems3, such as:

  • Insomnia
  • Sleep Apnea
  • Narcolepsy
  • Limb Movement Disorders

Reinforcing Good Sleeping Habits

After receiving sleeping metrics, it’s time to evaluate where you lack and where you can improve. For example; if you receive information that your sleep time was disrupted on day one and four, it’s time to reevaluate what might have caused this:

  • Frequent naps during the day
  • Insomnia
  • Environmental factors

Data collection is important to be able to reinforce better sleeping habits from thereon. For example; if environmental factors are in play, such as:

  • Snoring partners
  • Loud neighbors
  • Parties downstairs

Your best bet would be to invest in noise-canceling earbuds or adjust your timings where these factors aren’t in play. If the case is insomnia, you might consult with sleep medicine experts for medication. For frequent napping, you would have to adjust your schedule enough to receive one proper night’s worth of sleep.

Recognize Sleeping Patterns

The data on your fitness tracker heart sleep monitor is a collaboration of heart rate and body movements. Making it somewhat relatable to the quality of your sleep and completely relatable to the quantity of it.

Compare the amount of sleep you’re getting one day with the next, or compare week one with week two. The difference in the type of sleep you receive will help in monitoring sleep cycles better and maybe even seeking professional advice.

Also, given guidelines for the duration of REM and NREM sleep cycles, you might be able to correlate when you were in deep sleep compared to when you were borderline awake. Again, the human body can do well without REM sleep, but it won’t be able to survive (yes, a lack of sleep can be fatal) without NREM sleep.


In conclusion, sleep is one of the most important parameters of health. Fitness bracelet brands often have sleep trackers installed in them that work with the help of accelerometers. These devices recognize shifts in heart rates and body movements. While fitness trackers aren’t accurate for indicating sleep cycles, they have accuracy over the duration of sleep, the factors involved, and allow people to make comparisons. All in all, a sleep tracker in your fitness bracelet can help in improving the quality and quantity of your sleep.

December 16, 2020


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