Sleep score doesn’t match Fitbit explanation

[JDNTX]

I would like more information about how sleep score is calculated, especially the sleep stages. I have read the description provided in the FAQs, which basically says the more you are in REM and Deep sleep, the higher that score. I have experienced several nights where I have had much higher than average REM and Deep sleep, and less light sleep and awake time, only to have a lower than average score. Not sure if this is a recent change to the algorithm or something wrong with my app or what, but it is very confusing to me. 

[JohnnyRow]

But also doesn't it say total time asleep is 50% of the score.

[LZeeW]

Hello @JDNTX and welcome to the Community.  Your sleep score has three components, but they carry different weight to your total sleep score.  Help article with relevant section expanded  You don't mention whether you have Premium or not.  You also don't mention whether you are referring to your total sleep score or just the Deep/REM portion.

• Duration: Time Asleep and Awake.  This accounts for 50% of your score.
• Quality: Deep and REM sleep.  This accounts for 25% of your score 
• Restoration: Sleeping heart rate and restlessness.  This accounts for 25% of your score

If you are looking your total sleep score, it's very possible to have exactly the same amount deep and REM on two different days, but two different total sleep scores.

Does this help?

[JDNTX]

I have premium and am able to see all the details, including the breakdown of the three components of the score. I am specific talking about the 25 points for the Sleep Stages portion of the score. (Sometimes I wonder about the sleep duration portion of the score also, but the sleep stages is the one that doesn’t track to the description in the most obvious way). Thanks for helping me clarify. 

[LZeeW]

@JDNTX   I think the magic word here is that Fitbit uses a proprietary algorithm.  I'm sure it looks at when different stages occur during sleep or if are there long periods or a whole bunch of short ones, things like that.  We see aggregate amounts, not the fine details.

One thing I can say is my highest score for my sleep stages (24/25) happened when both Deep and REM exceeded my Benchmark data.