According to an Apple support page[0],

> With Apple Watch Series 3 or later with watchOS 8, you can measure and track your Respiratory Rate.2 With Track Sleep with Apple Watch turned on, when you wear your Apple Watch to bed, it will automatically measure and record the number of times you breathe in a minute.

I assume that this information is enough to warrant "go see a sleep specialist", but possibly not much more than that. There is at least one watchOS app that claims to use the Apple Watch data to detect sleep apnea[1], though it may not be a completely reliable source[2].

With Apple's increasing focus on the health for the Apple Watch, I would not be surprised if future watchOS updates (or future Watch hardware) focus on sleep apnea detection as a flagship feature.

[0] https://support.apple.com/en-us/HT211685

[1] https://9to5mac.com/2022/05/10/napbot-sleep-apnea-analysis/

[2] https://www.reddit.com/r/SleepApnea/comments/vxkkxx/napbot_a...

For WatchOS, you would start by running the Sleep App[0] and notice that there is an issue with your sleep stages.

Next you might move onto an app, like SnoreLab[1] where you record the audio of your sleep each night and can listen back to where you are having sleep interruptions. At that point, you would likely hear your breathing process.

Moving onto the Withings Sleep Analyzer[3] (as shown in the article) will fill out your data but by step 2, you will should probably already be setting up an appointment with your doctor for sleep apnea.

[0] https://support.apple.com/guide/watch/track-your-sleep-apd83... [1] https://www.snorelab.com/ [3] https://www.withings.com/be/en/sleep-analyzer

It can detect bad sleep patterns, and modern versions can detect pulse-ox, but not specifically apnea, AFAICT. It is definitely a useful too, and there are cheaper alternatives (I’m using an $80 Garmin) that give “good enough” info for personal tracking, but in my experience, Drs. don’t care about it.