Fitness trackers are very useful companions for our daily lives and can give you that extra incentive to get active. But using the smart bracelets only during the day would be wasted potential, because after all we spend about one third of our lives sleeping. So why shouldn’t you wear your fitness tracker at night as well? Some devices can monitor your sleep patterns and promise to help you wake up happier and more refreshed.
But how useful is it to track your sleep with a fitness tracker? In this article, we’ll take a look at the most important questions about sleep trackers and look at the best models. Have fun! 😉
What is Sleep Tracking?
Sleep is such a complex topic that it is obviously not possible to deal with it entirely in just one article. Bad sleep leads to bad mood, unproductivity and can also cause health problems, while a good and balanced sleep is the foundation of a successful and positive day.
I am sure that each one of us knows those days when you just get up on the wrong side of the bed. But how do you even know if you have slept well or not? And what can you do to ensure a good night’s sleep?
The best option here would certainly be to have your sleep examined in a sleep lab. However, it is not every day that you have the time and money to be wired up in a laboratory and for most people, it’s not quite easy to fall asleep in a lab environment.
Luckily, you can now wear sleep trackers on your wrist. But can you really rely on such a portable mini sleep lab? Before we can answer that question, we first have to look at the different stages of our sleep and understand how the fitness bracelets are tracking them.
The Sleep Cycle and its Sleep Stages
If you’ve ever searched for sleep advise on the Internet, you have surely stumbled across the terms “sleep cycle” and “sleep stage”. There is so much information and even more rumors about this complex topic, that it’s very easy to lose track. Let’s try to shed some light on how our sleep actually works! 😉
Did you know, for example, that at night, we usually wake up about 4-6 times? Its only very short periods of time and therefore we usually don’t even remember it the next morning, but we actually wake up a few times every night.
Additionally, you should know that sleep is not uniform. Instead, your total sleep consists of several sleep cycles that are composed of different sleep stages. We usually live through 4-6 sleep cycles every night. Each cycle lasts about 90 minutes and is, like I said, divided into different sleep stages. And this is where it gets exciting.
Researchers often divide our sleep into 4 or 5 different sleep stages – stages 1, 2, 3 and sometimes 4 for the non-REM sleep and the REM-sleep. However, most wearable sleep trackers keep things simple and group similar sleep stages together. As a result, your sleep will be divided into light, deep and REM sleep stages.
Light sleep is the initial stage of a sleep cycle. Our muscles start to relax, our brain activity is slowly reduced and our eyes hardly move at all.
Body and mind relax little by little and yet we are not yet sleeping deeply. This is expressed above all in the fact that we still move quite a lot in this stage. We turn around a lot and it would be very easy to wake us up. That doesn’t sound really relaxing, but remember that this is just the first sleep stage.
Light sleep takes up most of our total sleep, each individual light sleep stage usually lasts between 30 and 60 minutes.
The light sleep stage is followed by the so-called deep sleep stage. As you might guess from its name, this stage has us sleeping like a rock and waking up now would have us feel like woken up on the wrong side of the bed.
It is during deep sleep that the body and mind recover most, which is why it’s also considered the most important sleep stage. Everybody knows these nights, where we dozed off again and again, but never really slept deeply. It is important that we go through several deep sleep stages per night so that we can start the new day with a lot of energy.
How long does a deep sleep stage last? That varies greatly. The deep sleep stage in the first sleep cycle is usually about one hour long, but that decreases significantly with the following sleep cycles. The first sleep cycles are therefore particularly important, as this is where our body recovers most.
Following the deep sleep stage, our body returns to the light sleep stage before moving on to the so-called REM sleep stage. In contrast to the light and deep sleep, the REM sleep makes it more difficult to derive something from its name, but basically this stage is easy to understand as well.
REM is the abbreviation for “Rapid Eye Movement”. And unsurprisingly, rapid eye movements are an important characteristic of this sleep stage.
But what makes this stage different from the others? Physically not much. The body is still deeply relaxed and hardly moves at all. But our brain plays its own game and is now much more active again.
In this stage we process the activities and experiences of the day. Our heart rate rises slightly and our brain activity increases significantly. This is the reason why most dreams occur in this stage, some of which can be very vivid. And this is also the reason why fast eye movements are more frequent. Basically, our body behaves as if it were awake, except that we are not moving. You could say that the brain is very active during REM sleep, while the body is very inactive.
The lengths of the individual REM sleep stages are exactly opposite to those of the deep sleep stages: While the first REM stage lasts only about 10 minutes, it can take up to an hour in the early morning. This is why usually, we are experiencing the most vivid dreams in the early hours of the morning.
How do Sleep Trackers Work?
Phew, that was quite a lot of information at once. Actually, you are a real expert now when it comes to sleep. 😉 In order to use this knowledge meaningfully and improve our sleep quality, we not only need to know which sleep stages exist but also, how much time we usually spend in those sleep stages.
Modern sleep trackers promise you exactly that. Undoubtedly, the smart bracelets are useful in many respects, but how do they track our sleep stages?
Fitness trackers mainly work with accelerometers. They measure how many steps we take each day and how active we are in general. But motion data can also be useful at night.
During light sleep stages, as already mentioned, we start to relax but still move quite a lot. In the deep sleep and REM stages, in turn, we are hardly moving at all.
Sleep trackers can therefore use the motion sensor to determine whether we are in light sleep or deep sleep. In order to be able to distinguish between the deep and REM stages, we’ll additionally need an optical heart rate monitor, which is now a standard feature of modern fitness trackers.
Since the heart rate is slightly increased due to the increased brain activity in them REM stage, it is easy to distinguish between the two stages.
The combination of motion and heart rate measurement is what ultimately helps fitness trackers to monitor and analyze our sleep.
Are Sleep Trackers Accurate?
That sounds all well and good, but let’s be honest: Can sleep trackers really track our sleep accurately?
Well, it’s hard to say. One thing should be sure: Wearable sleep trackers will certainly not be able to track your sleep to a level of accuracy that researchers in a sleep lab will.
Fitness trackers measure our sleep stages based on motion and heart rate data. However, it is also possible that we lie in bed calmly, not moving, but still being awake. Our body is deeply relaxed, but our mind is simply not yet in sleep mode.
In such a case, sleep trackers cannot know whether we are really asleep or simply very relaxed. In order to track your sleep with perfect reliability and validity, you need access to your brain activity and that’s simply not possible with a bracelet.
Nevertheless, the trackers are not completely useless either. After all, they can give us a rough idea of how well or badly we sleep. For example, if we move around a lot at night or have a comparatively high heart rate, this is already a sign of a rather restless sleep, in which the deep sleep stages may have been a little too short.
The bottom line is that sleep trackers can give us a good first idea of our sleep behavior, but if sleep deprivation or poor sleep really becomes a problem, we should not rely on the results of the wearable sleep trackers, but rather see a doctor or do a professional sleep analysis in the lab.
The Smart Sleep Alarm: How to Wake Up on the Right Side of the Bed
Unfortunately, fitness trackers cannot provide the accuracy of clinical research, but they can still be very useful. As we have just seen, fitness bracelets are quite capable of detecting whether we are in the light or deep sleep stage based on our motion and heart rate data.
Whether we get out of bed on the wrong side of the bed in the morning or start the day refreshed and energized has a lot to do with whether we were woken in the middle of a deep sleep stage or gently awakened from a light sleep stage.
If we are awakened from a light sleep stage, we feel much more refreshed and can start the day with a lot of energy. Modern fitness trackers therefore offer so-called smart sleep alarm clocks that recognize our current sleep stage and try to wake us up at the time we’re likely to feel the most rested.
So we do not set a specific time for the alarm, but a certain time frame, such as 7:00 to 7:30. The fitness tracker then tries to find out the best possible time spot within this time frame to wake us up, i.e. during a light sleep stage.
Again: Sleep trackers are not 100% accurate and certainly cannot replace a professional analysis in a sleep lab. But if we are still moving very, very little at 7 a.m. and have a very low heart rate, then this is definitely an indication of a deep sleep stage.
If the tracker recognizes that our movements increase at 7:15 a.m., then it is quite possible that we are now entering a light sleep stage. Being awakened here would probably be much more pleasant than 15 minutes before and we can start the day more refreshed and with more energy.
What is the Best Fitness Tracker for Sleep Tracking?
Fitbit Versa 3
Fitbit is probably the most popular manufacturer of fitness trackers and has already convinced many people worldwide with products of the highest quality. The American fitness giant is also at the forefront when it comes to fitness trackers with sleep monitoring.
But this has not always been the case, after all, they have long done without the smart sleep alarm feature so eagerly desired by their followers. With the latest update, this very useful feature has fortunately been added to some models.
Among those the Fitbit Versa 3, which I consider to be one of the best fitness trackers anyway. This device impresses with its suitability for everyday use, the very good sleep tracking and last but not least with its strong price-performance ratio.
The Fitbit Versa 3 is equipped with motion sensors as well as an optical heart rate monitor, both of which provide a very good sleep analysis within the possibilities of a fitness tracker.
Additionally, you’ll get the amazing Fitbit app, which helps you to compare the sleep data of different nights and keep track of your overall sleep quality. You’ll get an idea of how much time you spent in the light, deep and REM sleep stages and get tips on how to further improve your sleep quality. Fitbit also offers guided breathing exercises to help you relax during the day and become more relaxed in general.
And as I already said, the Fitbit Versa 3 also comes with a smart sleep alarm. For this reason, I think that the Fitbit Versa 3 is the best fitness tracker for sleep tracking at the moment. But because this is just my humble opinion, I’d suggest that you take a look at this tracker for yourself. Here you will find it.
Fitbit Charge 4
Another Fitbit device. The Fitbit Charge 3 was the number 1 fitness tracker for a long time and still enjoys great popularity. In 2020, the keenly anticipated successor model was launched: The Fitbit Charge 4!
Many people were happy that finally, yes, finally the Fitbit Charge comes with a smart sleep alarm. The sleep stages could already be tracked in older versions of this tracker, but the 4th generation is the first one promising to wake you up at the time you’re likely to feel the most rested.
The Charge 4 is the first classic fitness bracelet from Fitbit to be equipped with this feature. Another nice feature of this fitness tracker is the integrated GPS, which allows you to track your trails without having to pair your phone. In terms of its features, this tracker is on the same level as most smartwatches, yet it is a lot lighter and smaller.
In the end, it’s all a matter of taste. One thing is for sure, the Fitbit Charge 4 is yet another very good fitness tracker for sleep tracking. Again, I would recommend that you take a look at this device for yourself. Here you will find it.
Huawei Band 4 Pro: The Best Budget Tracker
If my previous recommendations are a little too expensive for you, then you should take a look at the Huawei Band 4 Pro, that is probably the best low-budget fitness tracker at the moment.
Even though it will not cost you more than 70 dollars, this tracker provides a decent sleep tracking feature. It comes with a smart sleep alarm and helps you start the day refreshed. With the included app you can easily set a wake-up time frame.
Compared to the previous models you have to do without some additional features, but you’ll still have the most useful features, like an optical heart rate monitor, motion sensors, integrated GPS and sleep tracking.
In my opinion, you can hardly get a better fitness tracker for that price. So it is definitely worth taking a look at this device as well. Here you will find it.
Final Thoughts on the Best Fitness Trackers for Sleep Tracking
We spend about one third of our life sleeping. A good and restful sleep is one of the most important keys for a life full of energy and joy. Nevertheless, many of us suffer from sleep disorders, which is why it is time to pay more attention to how we can improve our sleep quality. A fitness tracker cannot replace a scientific sleep analysis in the laboratory, but it can still give us a first impression of our sleep quality and help us to wake up on the right side of the bed.
I hope that I could help you with this article. However, if you have any further questions on this topic, feel free to contact me.
Otherwise, I wish you a lot of fun with your new sleep tracker! 😉