How are recommended sleep stage percentages calculated?

July 30, 2023 2:13 PM

Experts recommend the typical adult get 7-8 hours of sleep a night, and roughly 20-25% of this be REM sleep. Is the 20-25% recommendation based only on active sleep stages (ie do not count awake time) or on total time in bed as the Apple Watch does?

I have an Apple Watch that records the sleep stages as a percentage of total time in bed. Since I have a newborn my ‘awake’ time is pretty significant overall. So for example if I’m ‘in bed’ for 8 hours, and I am awake for 3 hours during the night, and I am in REM sleep for 1 hour, then Apple Watch says my REM sleep was 12.5% of my sleep and not 20%. How do I interpret the results from this perspective?

posted by TwoWordReview to Health & Fitness (2 answers total)

As I understand it, it takes your heart rate and calculates the different sleep stages from that. There’s some subtle variations in heart rate only seen in those states. I had two different trackers (muse and fitbit) both give the same result in one night so pretty consistent.
posted by St. Peepsburg at 3:22 PM on July 30, 2023

I have no idea why Apple is calculating anything from "in bed, but not asleep" time. My Oura calculates the REM sleep as a percentage of detected sleep time, not "in bed" time.
posted by meowzilla at 6:06 PM on July 30, 2023