How Accurate is Fitbit Sleep Tracking? What Researchers Says

Since the last few years, Fitbit has made several definitive changes to its fitness tracking system. There was a time when people used to complain that the data provided by Fitbit trackers weren’t really up-to-the-mark especially when it comes to sleep tracking. However, now, Fitbit has changed the viewpoint and opinion of customers with its latest best fitness trackers and smartwatches like Fitbit Sense, Charge 4, etc. So, do you really want to know how accurate is Fitbit sleep tracking

How Accurate is Fitbit Sleep Tracking

Let’s check it out together. 

How Accurate is Fitbit Sleep Tracking

Fitbit Accurately tracks your sleep with the help of its sensors and other advanced algorithms. The Fitbit wearables can track sleep more accurately as it comes with advanced health tracking features such as blood oxygen level monitoring, heart rate monitoring, etc“.

Before we answer the question, let us check what researches says about Fitbit sleep tracking. Here is detailed research on Fitbit Sleep Score and its accuracy done by the NCBI.

What Do the Researches Tell About the Efficiency of Fitbit Tracking System?

A few years ago, some prominent scientists decided to check the accuracy of the Fitbit tracking system by conducting a study on over 3,000 individuals. During the non-sleeping stage, the devices from Fitbit had exhibited an accuracy level of 0.81 to 0.91, which is almost perfect. Further, it had also marked a sensitivity level of 0.87 to 0.99.   

Moreover, it also had exhibited specificity values if 0.10 to 0.52. On the other hand, while an individual was sleeping, the Fitbit sleep tracker provided 0.95 to 0.96 of the sensitivity level. Additionally, the specificity level had increased (0.58 to 0.69) as well. Nonetheless, the accuracy level stayed the same as the non-sleeping mode, which evokes the notion of its consistency.

How Do the Fitness Trackers Track Sleep? 

Unlike the conventional ones, almost all the modern fitness trackers can track your sleeping schedule. But how do they do so? Well, let’s take the example of the Fitbit Sleep Tracking system to understand more about it. If you do not move from one place to another for around an hour, then the other brand’s devices will assume that you are sleeping. 

However, that’s not the only parameter a Fitbit tracker measures while tracking your sleeping program. Besides, it also takes a few additional data into account, such as your movements (rolling over), which are aligned with the usual sleeping behaviors. Once it has confirmed that you are actually snoozing, it will then start tracking through the various sleep stages. 

But what are the sleep stages? How do they even track them appropriately and create the ultimate Fitbit sleep score? Make sure to keep reading if you do want to get answers to these questions.

Different Stages of Sleeping  

Most doctors tend to categorize the sleeping pattern of a healthy person into three stages. Here are a few details about each of them. 

Light Sleep 

Light sleeping is generally known as the initiator of your sleeping timetable. During this phase, the muscles, especially your hands and legs, start relaxing a bit. Besides, your heart rate, too, begins slowing down a little bit. However, if you encounter any sound or disturbance in this stage, you may wake up quickly. 

Most of the best sleep tracker systems from Fitbit generally track the light sleeping phase by assessing the following actions. 

  • Small jerks in the muscles. 
  • Decreasing heart rate. 
  • Drops in the overall body temperature.
  • Moderately slow respiration.

Deep Sleep

Unlike the previous one, during deep sleep, your body starts regenerating and reinvigorating itself. Moreover, your brain, too, begins to remove wastes from its internal section. Hence, if you do awake during this phase, then you may act a little bit groggily.

So, to keep track of your deep sleeping manners, the tracker may evaluate your –

  • Drops in blood pressure. 
  • Slow yet long brain waves. 
  • Little to no movement. 
  • Lower body temperature. 

REM Sleeping

The REM sleeping stage usually occurs when you are dreaming or solving some problem while snoozing. However, the overall duration of this particular stage generally decreases as you age more.

Nonetheless, the Fitbit sleep trackers can trace this situation as well. It usually does the same by tracking the following manners.

  • An increase in respiration flow 
  • Suddenly elevated heart rate 
  • Either too much of movement or nothing at all. 

To evaluate the sleeping stages accurately and adequately, a sleep tracker has to assess the heart rate. Further, it would have to estimate the blood oxygen value frequently as well. 

Otherwise, it will become almost impossible for the device to calculate your sleeping stages precisely. 

Fortunately, almost all of the sleep tracking devices come with both of these features. Due to this reason, the Fitbit sleep tracking accuracy always stays at a top-notch condition. 

Why Does Fitbit Provide More Accurate Results than Other Trackers?

There are several reasons which help the Fitbit trackers to provide much better and precise results than the other similar products. For starters, Fitbit’s devices come with a heart monitoring component, which helps it assess your current heart rate. While sleeping, your heart tends to beat a little bit slower.

Hence, by assessing the same, the device can assume that you are currently sleeping. Aside from that, your blood’s oxygen-carrying capacity, too, tends to drop a little bit while you are snoozing. So, sometimes, the tracker also measures VO2 Max and your blood’s oxygen level to evaluate your current situation. 

As mentioned before, the heart rate and blood oxygen level tend to change during different types of sleep stages. Thus, if the device can follow these particular features of your body, then it can, undoubtedly, track your sleeping system profoundly and accurately. Due to this reason, the data provided by the Fitbit devices tend to be precise and perfect. 

What are sleep ranges?

You can see your sleep score in the Fitbit App, and it gives you a detailed insight into the quality of your sleep. 


Your sleep score and other sleep data collectively help you to improve your sleep pattern by making some modifications to your sleep route. 

Best Fitbit Devices for Sleep Tracking

There are several best Fitbit for sleep tracking available in the market. Hence, naturally, choosing one among them can be a little bit difficult for you. Thus, to help you out in this aspect, we have narrowed down the list a little bit. Hopefully, it will help you out in your endeavor.  

Fitbit Charge 4: Fitness Tracker with Smart Alarm

When talking about the best Fitbit for sleep tracking, the first name that comes to the mind is Fitbit Charge 4. For starters, the product comes with three different sleeping modes for tracking your schedule accurately. It will arrange your sleeping score by following the phases of light sleep, deep sleep, and REM sleep properly.

Secondly, the model comes with a unique feature called Sleep Mode. You can activate it by pressing the left button for a few seconds and then swiping to the right side. Once enabled, this mode will dim the display slightly so that you do not have any issue while sleeping. Moreover, it will also silence the texts and calls after activation. 

Last yet not least, there is also the Smart Wake/Smart Alarm feature available in the product. It uses special machine learning procedures to help you to wake up at an optimal time. However, it only does so when you are light sleep. 

Fitbit Charge 3

Yes, you have understood it correctly. The Fitbit Charge 3 is, indeed, the former variant of Charge 4. However, it doesn’t mean that the former is inferior to the latter in any way. For starters, like Charge 4, this one, too, can record the amount of time that you have spent in REM, deep, and light sleep.

Moreover, it also offers you several healthy sleeping insights to make you stress-free and sleep comfortably. Besides, the model, like its advanced variant, can track your heart rate as well. Therefore, it will provide you with accurate sleep data without failing. It also has a decent battery life of around seven days.

However, unlike Charge 4, this one does not feature the Smart Wake mode. So, you will have to set the alarm separately before going to sleep! There are a few color options, too, available about the product. So, you can choose anyone that suits your taste. 

Fitbit Versa 2

The Fitbit Versa 2 is one of the costliest smartwatches of the brand Fitbit. Hence, as expected, it does come with many features that can help you track your sleeping prowess. Firstly, it can help you check your heart rate and blood oxygen level without any error. Thus, it will be a lot easier for you to know about your health condition in a proper manner. 

Also, like both of the previous models, Fitbit Versa 2, too, can appropriately track your sleep pattern. It does so in three different stages: light sleep, REM sleep, and deep sleep. Once you have woken up, you can find all the details as well as your overall sleep score in an organized manner in the Fitbit App. 

The watch does not feature any features like the Smart Wake system at all. However, there is an alarm system in Versa 2 that can help you wake up at a precise time in the morning.

Versa Lite 

Are you thinking about buying a less expensive yet efficient model from Fitbit? Then, Versa Lite should be an ideal option for you. It comes with over 15 different sports mode and properly records your workout schedule. Moreover, it also monitors your heart rate all day long, especially when you are working out. 

Besides, while you are sleeping, the device also starts tracking the oxygen level of your blood. It, in turn, helps it to track your sleeping mannerism as well. Even though it is a lot more affordable than the other models, it can still help you set the in-built alarm and wake up whenever you want. It is quite loud, so it will definitely awaken you.


So, hopefully, you have gotten your answer about how accurate is Fitbit sleep tracking! Now, it becomes your job to choose the best one of all the mentioned products. With a little bit of luck and a tad bit of research, you will surely be able to find the one that suits you perfectly.  

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