Hacker News Reader

Comment by abtinf | Hacker News Reader

I’ve always wished I could put Apple Watch into a “constant oxygen monitor mode” for sleep. That seems to be the obvious way to assess sleep apnea.

Anyone know why that isn’t the method?

View on HN

There's a ton of cleverness involved in keeping an extremely compact device with radios and sensors running for tens of hours on a tiny battery while making it seem like it's always awake and ready to go when you need it to be.

But the reality is that everything that needs any kind of power is being aggressively idled down and time sliced and being made sample-based as can be gotten away with. You can easily get a sense of this with heart rate monitoring, if you dig into Apple Health and observe the pattern of samples it takes.

Almost certainly, running the sensor at such a high frequency that you could call it "constant" would drain the battery long before you woke up.

To be frank: I think what you're saying is true only of the Apple Watch, and Apple is wrong to believe that their priorities are the ones which would resonate most with their customers. Bands from Garmin, Whoop, and others have 24/7/365 sensor collection, with battery life measured in days and weeks.

Apple instead prioritizes 3000 nit displays, laptop-class processors, and 60fps touch interactions. These are all characteristics which make for great keynote slideshows, and maybe even close a lot of "first time smartwatch" sales, but I simply don't encounter anyone who wouldn't trade much of that for an Apple-made device that lasts 3+ days and has higher resolution sensor collection. The sleep apnea detection alone is, while interesting, something of a farce when it was followed up with a "18 Hour Battery Life" slide; yes you can make it work, but its an active decision by Apple to ask you to, and it doesn't have to be this way.

> 18 Hour Battery Life

Didn't see the slide by my apple watch definitely lasts way longer than 18 hours. But, I also have the screen default to off instead of always on (lets be real, who spends all day staring at their watch; motion activated turning on seems like not even a compromise).

The Series 10 is confirmed for 18 hours, like the Series 9 before it. The Ultra will definitely last longer. The Series 9 can as well, if you turn off features which Apple advertised the Apple Watch as having, and if you do not record a single exercise throughout the day. If you use the watch how it was advertised, it will last ~18 hours, which means if you charge it overnight, wake up at 7am, are awake for 16 hours, it will not survive the night.

Its not helpful, productive, or useful to state that you turn off headline features people paid to have in order to get greater battery life than even Apple advertises the device as having. Please adjust your discourse and do not repeat your behavior.

1. Because of the lawsuit around the pulse oximeter intellectual property, as other commenters mentioned.

2. That would require more battery life than the Apple Watch offers.

There are third-party options that do constant monitoring that either directly or indirectly support Apple Health. You'll need some additional intelligence, in the form of an app or something, to analyze that data. WatchOS won't do it at present.

They still don't have the regular oxygen monitor mode back yet because of a patent dispute. That might be part of it.

That's only in the US, right?

(My flimsy understanding is that blood oxygen measurement is how at-home sleep studies work?)

At-home sleep studies measure heart rate (maybe ekg, some probe is on your skin), blood oxygen, sound, and the direction of gravity relative to your testing device (to classify results by "back", "side", "prone", etc.)

I did one of these and it was the worst night of sleep I ever had. It's somewhat invasive. Meanwhile, I sleep with my watch every night with no problems.

Interesting. I keep meaning to get one done. Probes don't seem like that big a deal?

They really clamp your finger in the pulse oximeter probe, and it's taped with one-time-use adhesive. So there is no taking it out when it hurts, you just have to live with it and try to sleep. The instructions say "it's not that bad, you'll be fine".

I got some sleep.

I think this depends on your doctor/clinic and where you are. The last one I took home just had an oxygen sensor and the skin probe/patch. The doctor said they get (hand wavey) 95%+ of the same diagnostic capability from the simpler setup and far fewer claims of poor quality sleep caused by the equipment.

Amusingly my Apple Watch pulse ox showed low so I did a sleep study. It's invasive, but it plugs into your nostrils (and in my case held them open). Slept like a baby. Next day 99% was the lowest reading. No problem. Now I use these sleep strips from this company called Intake. Sleep well. Holds nose open. I have a deviated septum, apparently. I think it's from falling off a tree onto my nose as a child, and being hit in the face by basketball numerous times. But probably not.

What was funny was that at-home sleep study was damned good sleep because it held my nose open!

Yeah, you’re right.

If I had to venture a guess, maybe it's an industry regulation or power usage issue. Simply being able to assess sleep apnea isn't enough, it has to pass the regulatory burdens as well.

PAT uses oxygen, so they actually do use exactly that.

Reply on news.ycombinator.com