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Fitbit and sleep tracking – everything you need to know

Approved by our Clinical team | May 3, 2021

Whether you have a Fitbit or not, you’ll probably know that it works by tracking your activity – most famously, your daily step count. What you might not realise is that this little gadget can be used to track other health data, including meals, workouts, and even your sleep.

Tracking your sleep with your Fitbit can be a great way to cultivate a better night-time routine, and in turn improve your overall health.

What does the Fitbit sleep tracker do?

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When you wear your Fitbit on your wrist while you sleep, it can record a few different things including:

When you went to sleep
When you woke up
When you were restless
The stages of your sleep

For the best results, Fitbit recommends wearing your device about two to three finger widths above your wrist. The band shouldn’t be too tight, but it should be secure enough that the monitor sits against your skin.

Sleeping and waking

If you’re completely at rest and not moving for about one hour, your Fitbit will begin to record your sleep. It will record any period of sleep throughout the day (even a nap on the sofa) provided it’s at least an hour long.

When you wake up you’ll be able to see how long you slept. Your Fitbit will calculate this figure by subtracting any time spent very restless or awake from your overall sleep time.

Restlessness

Your Fitbit can detect when you’re restless by how much you’re tossing and turning. At a certain point, restlessness will be counted as time awake.

It’s worth bearing in mind that it’s very common to be restless or to wake up fully during the night. Don’t be surprised in the morning if you see that you have several awake periods during the night – even if you don’t remember them.

Sleep stages

If your Fitbit has a heart rate sensor, it can detect the stages of your sleep.

Each night in bed, your body goes through several sleep cycles which last about 90 minutes each. These cycles contain periods of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep.

NREM sleep incorporates light sleep and deep sleep
REM sleep is when your brain is most active and you’re having dreams

In a standard sleep cycle, your brain goes from light to deep sleep, then back to light sleep, before entering the REM stage. Over the course of the night, you might go through four or five of these 90-minute cycles.

When you wear your Fitbit to bed it can provide a good estimation of your sleep stages by monitoring your movement and heart rate. During REM sleep, for instance, heart rate tends to increase, which can be detected by your Fitbit.

Why should I track my sleep with a Fitbit?

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Tracking your sleep can be a good idea if you regularly struggle to get your forty winks.

Ongoing lack of sleep can have a serious impact on your health, affecting your immune system, increasing your blood pressure, and making you more prone to diabetes and weight gain.

By wearing your Fitbit to bed you’ll have a better idea of how much sleep you’re getting. You’ll be able to look at your sleep across the week, and work out whether certain factors (e.g. whether you exercised that day or drank alcohol) might have affected your sleep.

How can I use my Fitbit to get better sleep?

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The Fitbit doesn’t just record information about your sleep – it also comes with functions that help you set a better sleep schedule.

You can set a bedtime target, a wake-up target, or both. You can also set a bedtime reminder, which notifies you in advance that it’s time to start winding down.

Fitbits also come with a silent alarm, which vibrates and flashes at the set time, providing a gentle wake up. In some newer models you can set your alarm using Smart Wake. This activates 30 minutes before your alarm is set, and attempts to wake you at the optimal time i.e. when you’re not in deep sleep.

What are the other health benefits of using a Fitbit?

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Any smart watch or activity tracking device like the Fitbit can be really beneficial if you’re trying to lose weight and do more exercise.

You can easily keep track of your exercise across the week, recording step count, periods of intense activity, and estimated calories burned. This will help you set goals, and demonstrate how much you’re improving. You can also use the Fitbit to log your meals, which will help you keep track of your daily calorie intake.

The Fitbit can also be beneficial for your mental health. Fitbit has a Mindfulness feature with short guided sessions, and a Relax function, which encourages you to take a short breaks from your day for some deep breathing. If you have the Fitbit Sense you’ll even be able to track your stress and receive guidance on managing it better.

Find out more by browsing the different Fitbit models available.

The benefits of better sleep and how to get it

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According to the NHS, good sleep can…

Boost immunity
Help you avoid weight gain
Improve your mood, reducing depression and anxiety
Increase sex drive
Reduce the risk of heart disease
Increase fertility

Improving your sleep isn’t always easy, but there are some simple things you can try. Sleeping at regular hours and sticking to a routine is really important, as is giving yourself time to wind down. If possible, make changes to your bedroom to make it darker, quieter, and in general a more relaxing environment.

For more tips, read our article: How to get a good night’s sleep.

References

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Fitbit and sleep tracking – everything you need to know