Inconsistent sleep tracking data between Apple Watch and another app

Dooow wrote:

Sure, but besides the sleep tracking and the hours, I care about this because I might have sleep apnea, and it’s pretty important

The watch needs to have measured 10 sleep episodes within 30 days. If it's off by a couple of hours in any given episode, that's not going to make a difference for the purposes of looking at sleep apnea. It doesn't notify you of sleep apnea in real time. It gives you an overall rating for the night. According to Apple, "If Apple Watch detects elevated breathing distances over multiple nights, the Health app will send a notification of possible sleep apnea."

The watch's sleep apnea detection feature, which uses the accelerometer to track breathing disturbances, has shown 66% sensitivity in identifying sleep apnea, meaning it correctly identifies that percentage of people with moderate to severe sleep apnea. For severe cases, the accuracy increases to 89%.

You may also find this article edifying:

https://www.tomsguide.com/wellness/sleep/sleep-apnea-experts-weigh-in-on-the-apple-watchs-latest-health-feature-heres-the-verdict

If you think you have sleep apnea, you should discuss this with your doctor.

Dooow wrote:

Sure, but besides the sleep tracking and the hours, I care about this because I might have sleep apnea, and it’s pretty important

Well, first consult your doctor to arrange for a real sleep test. No watch can accurately detect sleep apnea. You need a dedicated device such as an Oura Ring, which detects sleep apnea by monitoring blood oxygen levels continuously rather than indirectly by physical symptoms.

I have severe sleep apnea and I've found the tracking of breathing disturbances to be useful. I see significant differences between the nights when I use my CPAP and those when I don't for one reason or another.

There do seem to be some quirks in the way time asleep vs time in bed is reported. Part of that is based on whether you have the sleep focus set to kick in automatically based on your sleep schedule.

if you're seeing elevated breathing disturbances reported in the health app, you should definitely talk to your doctor about a sleep study.

Sleep tracking is something that's still problematic. It's useful for general trends but that's honestly about it.