Home / Sleep Tracker Reviews / How do Fitness Trackers Track Sleep?

How do Fitness Trackers Track Sleep?Fitness trackers have been all the rage for the past few years. When you think about how much they have to offer somebody who is tracking their progression in fitness, it is no surprise that they would be such a hot product.

From following your steps via a built in pedometer to calculate how many calories you have burned during your work out, these things do so much to help you stay on top of your health goals. But these are not the only areas where fitness trackers shine.

Sleep tracking

It is well known that one of the most important aspects of fitness is the rest that you give your body. When your body rests, it is also repairing any damages that it has undergone during your workouts (it is why body builders are so strict with their sleep schedules). Because sleep is the time that your body does the most repairing, it is essential that not only are you getting enough sleep but the proper amount of sleep as well.

Fitness trackers, when being worn, will track how many hours you have slept and how many times you have woken up throughout the night. This data will make it easy to tell what is going on with your body at nights and address any sleep concerns that you may have.

But how do fitness trackers do this? The answer is relatively straightforward even though the science behind how it works is extraordinarily detailed.

How do they track your sleep patterns?

The first thing that you will need know is that this feature does not work unless you are actually wearing it when you sleep.

The way that fitness trackers are able to track your daily activities is by using a 3-axis accelerometer to track your movements in all directions as well as how fast you are moving. The accelerometer tracks your movement throughout the day and will also be able to track your sleeping patterns throughout the night.

Steps you need to take

  • Make sure you wear your device at nights
  • Turn the fitness tracker on sleep mode to let it know you will be sleeping
  • Sleep

That’s all there is to it, and on some of the higher end fitness trackers you aren’t even required to do that much (obviously you still need to do the sleeping and wearing part, but step two isn’t always necessary though).

Fitness trackers with automated sleep functionality

The way these devices work is by detecting your movement over the course of time and using that to determine whether or not you are sleeping. This still works by using the 3-axis accelerometer that is inside of your tracker.

When we are asleep, we move a lot less than when you do while you are awake (this shouldn’t come as a shock to anybody). Because of this, once your fitness tracker has recorded little to no movement, or any movement that is an indication that you are sleeping (i.e. rolling over in bed(, after one hour your tracker will go into sleep mode.

Because it was already recording your activity while you were asleep, it will automatically transfer the data it has collected in that hour and use it as sleep data. This process measuring your sleep is called actigraphy. It is a surprisingly accurate process (especially when you take into consideration that is getting all of this information from your wrist), and it will track the movements of your wrist and use that to calculate and monitor your sleep.

Of course, this doesn’t work as well as polysomnography (the sleep tracking technology that professional sleep clinics use when determining if you have sleep disorders like sleep apnea), but it does perform remarkably well for a daily sleep tracker. When this technology is used for its intended purposes it does a tremendous job at keeping you informed and up to date with your sleeping habits.


Because the fitness tracker can only use the sensors inside of it, and those sensors are only located on your wrist, there can be mistakes that are made. While actigraphy is a genius technology, it is still one that involves a lot of guess work. This is just a by product of being limited by the number of sensors available.

It is possible for your fitness tracker to enter sleep mode falsely. Generally, this only happens if you spend an hour or more not moving (think of this feature as a reminder to get up and be active), but it is easily reversible by just deleting that sleep record from your dashboard.

Also, if you are a wild sleeper and move around a lot during the night, your device may translate that movement into you being awake. If you know that you fall into this category, you should just go ahead and put your fitness tracker in sleep mode before you go to bed.

How can this technology be used to increase performance levels?

It was stated earlier that one of the driving factors of progress in any type of fitness is giving your body the proper amount of rest. Fitness is all about bettering yourself, but to do that, you first have to break your body down a bit.

That is why we go past our comfort zones when exercising; we overexert ourselves so we can shock our body and force it to build itself just a little bit stronger each time.

But without getting the proper rest, all we are doing is breaking our body down and giving it no time to heal. Use the sleep monitor on your fitness tracker to determine what whether or not you have healthy sleep patterns.

Anytime you begin to notice that you are hitting a plateau, look at your sleep cycles. If you aren’t sleeping well, your device will make it visible to you.

From there all you will need to do is carry out the necessary adjustments to help you sleep better. Maybe eat dinner earlier, stop drinking caffeine after 4 p.m. or turn the tv off when you are trying to sleep. But the most important thing to remember is to wear your device when you go to bed.


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