How accurate is my REM sleep?

[Cass_123]

How accurate is REM on the Fitbit?

I know that you can only properly measure REM through brain waves, however I’ve seen a lot of people who trust the Fitbit. However, I feel as though my Fitbit is really off in REM sleep. Two nights ago, it says I got an 1 hr and 15 mins, but tonight it says I only got 15 minutes. It typically puts my REM as really low. I feel the exact same when I woke up both mornings- I don’t feel like I’m in a brain fog as most people say they do when I get little REM.

Is it my Versa? Or is my REM just really off?

thank you!

[HeydyF · Accepted solution]

Hey @Cass_123, let me give you a warm welcome to the Community! Remember that your sleep stages vary every night depending on factors such as a combination of your movement and heart-rate patterns. These ones are the more important. 

15 minutes of REM sounds very low, but maybe your Versa wasn't able to track your heart rate variability (HRV) as well as some other nights and that is why, maybe not only your REM sleep was affected but also your light and deep sleep. While you’re sleeping, your watch tracks the beat-to-beat changes in your heart rate, (HRV), which fluctuate as you transition between those stages.

In other words, if you think that your results aren't enough accurate, let me suggest you to take a look at the following scenarios: 

• If you slept in a position that prevented your device from getting a consistent heart-rate reading or wore it too loosely. For best results, wear your device higher on your wrist (about 2-3 finger widths above your wrist bone). The band should feel secure but not too tight.
• If you used the Begin Sleep Now option in the Fitbit app (instead of simply wearing your device to bed). For more information on automatic sleep tracking, see How do I track my sleep?
• If you slept for less than 3 hours.
• If your device’s battery is critically low

Give it a try for a few nights and let me know how it goes! 

[Cass_123]

Hello!

I have not been using the begin sleep now option. Should I be?

Thank you!

[Cass_123]

And what sleep positions can affect it?

[HeydyF]

Thanks for your reply @Cass_123! In order for you to get sleep stages, don't use the Being sleep now option, because the Charge 2 needs to track by itself your sleep data (along with your heart rate variability as I mentioned, in order to calculate light, REM and deep sleep. Now in regards of the positions, I would say that if you sleep with your arm under your head, for example when you are sleeping in fetal position, that could prevent your Charge 2 to record your heart rate well. It is better if your arms are more released, but sometimes we can't control the positions once we are asleep. 

For further information about how sleep stages work, take a look at this help article 

Keep me posted if you have further questions! 

[SunsetRunner]

Will the HRV measurement used for calculating REM be invalid because of my Pacemaker which keeps my low heart  rate at 60?

[RickNeon]

I don’t know if anyone is monitoring this blog anymore, but regarding the comment above about REM and having a cardiac pacemaker, i average around 20 minutes of REM on my fitbit sleep score since I got my pacemaker 3 months ago. Use to track 60-90 minutes before getting it, back when my heart rate was in 30s and 40s when sleeping.  I suspect I still have REM But not noted by my Versa which uses heart rate variations to detect REM. I imagine an EEG might show something different. 

[RichTechDevon]

I to have a pacemaker and cardiac tech says oxygen rate is an indicator or REM sleep And the fir me  REM sleep is about 40 mins, she thinks,, more than indicated on FitBit So realistically if you were 88 score you would be in 90s normally I add 5/6 to readings! Just a rule of thumb! 

[petew4]

I read that the fitbit uses hrv to measure sleep stages. Unfortunately, the fitbit is extremely innaccurate for hrv. It measures for me 14 ms, which is lower than even extreme 90 year-olds (note: higher is better). I was worried about this so I got an hrv monitor that is a strap around my chest. Fortunately, it puts my hrv at 50 ms.

So I wouldn’t trust the sleep stages measured by fitbit.