The sleep detection in your Polar device is fully automatic. It’s based on recording the movements of your non-dominant hand with a built-in 3D acceleration sensor. Although we, and others, have found the Sleep Plus algorithm pretty accurate, it's important to acknowledge the challenges of the automatic sleep detection technology. It’s possible that your Polar device will not be able to properly recognize your sleep every night, or that the detected times you've fallen asleep or woken up sometimes differ from your perceived sleep times. Within this document, we’ll explain why this can happen and what the challenges of automatic sleep detection are.
The Polar Sleep Plus feature has been developed for tracking healthy sleep. The metrics measured can help you better understand your sleep habits, and through that, find ways to optimize your sleep. The feature is not intended for use in the diagnosis or treatment of sleep disorders or other related conditions.
Sleep Plus metrics are missing for some nights
If your Sleep Plus metrics are missing it means that the Sleep Plus calculation has failed. This can be due to one or more of the following reasons:
- You slept less than 4 hours. Your sleep time, in other words the duration between when you fell asleep and woke up must be at least 4 hours to get Sleep Plus metrics.
- Your Polar device detected less than 4 hours of sleep, even though you actually slept longer than that. The automatic sleep detection may be challenging on nights when you are very restless and move a lot during your sleep, and therefore the data may be less accurate. The Sleep Plus calculation may fail, for example, if the detected time you’ve fallen asleep is later than the actual time and/or the detected time you’ve woken up is earlier than the actual time, and as a result, the length of sleep detected may be insufficient for Sleep Plus calculation.
- Automatic sleep detection is based on the fact that there is at least some movement during sleep, and as mentioned earlier, the sleep detection in your Polar device is based on recording the movements of your hand. If you are very still for long periods of time, it may be challenging for your device to ascertain that it is being worn. This might lead to inaccurate and insufficient sleep data in certain cases.
- Taking the device off immediately after waking up, or putting in on only for bed may confuse the Sleep Plus calculation.
Fell asleep / Woke up time is incorrect
If the detected time you've fallen asleep or woken up seems inaccurate, please check the following for possible reasons for inaccurate results.
- If you are very restless and move a lot during the start of your sleep, it may be challenging for your Polar device to recognize when you fall asleep, and therefore the detected time you’ve fallen to sleep may be later than the actual time.
- If you are very restless and move a lot during the end of your sleep, your Polar device may mistakenly detect that you’re awake when you’re actually still asleep, and therefore the detected time you’ve woken up may be earlier than the actual time.
- If you’re lying relatively motionless but not asleep for long periods of time before falling asleep or getting up in the morning (for example, while reading a book or watching TV), your Polar device may have trouble determining whether you are awake or sleeping, and it’s possible for your Polar device to falsely record sleep.
- If you’ve not worn the product for a while and you put it onto your wrist just before you go to bed, the device may not have enough data to ascertain that it is being worn. Try wearing your Polar device well in advance (about an hour and a half) of going to bed.
If you disagree with the detected times you've fallen to sleep or woken up, you can manually edit the times in the Flow web service or app to better reflect your time asleep
How to edit sleep times
- In the Flow web service go to Diary, and choose the Sleep tab.
- Choose the day you wish to edit.
- Choose , and then use the sliders at the ends of the sleep time to match your perceived wake-up time or fell asleep time. The maximum editing range is one hour longer from each end, or three hours shorter form each end.
- Choose Confirm when you’re done.
Click here to see how to edit your sleep in the app.
My Polar device doesn’t measure my Sleep Plus metrics at all
Try if resetting the device to factory settings would help. Running factory settings removes all personal data and settings from the device. You will need to set it up again for your personal use. All data that you have previously synced from your Polar device to your Flow account is safe.
Sleep Plus metrics are not shown under the Sleep tab but there’s sleep data in Diary
Throughout the years, our sleep measurement has been developed from the basic sleep data to Polar Sleep Plus. Although both features are based on recording your hand movements, the Polar Sleep Plus feature provides a deeper insight into your sleep, and therefore requires more specific data of your sleep for the calculation to succeed than basic sleep.
If the Sleep Plus calculation fails, for example due to insufficient sleep data, the Sleep Plus metrics cannot be shown for that night. In cases like this, we want to offer you a basic overview of your night sleep whenever the basic sleep data is available. You may see your basic sleep data in the Flow web service (Activity timeline and Activity summary) and app (Activity view). You’ll recognize the basic sleep data from the moon icon. The basic sleep data includes your sleep time and quality (restful or restless).
Activity timeline with basic sleep data:
Activity summary (in the day view of the diary) with basic sleep data:
Activity view in Flow app with basic sleep data: