I’ve been using an Oura sleep tracking ring for six months.<\/p>\n
In some ways it’s an impressive piece of technology. It’s small enough to not distract me much, and they went overboard in making the user interface simple. Simple, as in there basically aren’t any controls. I just put it on my finger, and occasionally put it on the charger.<\/p>\n
Yet it does a poor job of what I expected it to do: track how long I sleep. It occasionally thinks I’m in bed when I’m not wearing it. If I get up to use the bathroom, it’s hard to predict whether it will decide that’s the start or end of my time in bed.<\/p>\n
But the Oura reminded me that “8 hours of sleep” isn’t a good description of what I want – that’s just a crude heuristic for “slept well enough that further sleep won’t improve my productivity \/ health”. The Oura observes other relevant evidence: body temperature, breathing rate, heart rate, and heart rate variability. I.e. things I ignored because they were too hard to evaluate, rather than because I decided they weren’t important.<\/p>\n
If I did a strenuous hike yesterday, it will tell me that 7.5 hours of sleep wasn’t enough, whereas if I’d spent yesterday relaxing, it might have told me that 7 hours was plenty, and that I should be ambitious.<\/p>\n
It’s somewhat obvious that I need more sleep when a cold raises my body temperature. The Oura convinced me that there’s a much more general pattern of above average body temperature indicating an increased need for sleep.<\/p>\n
I’ve tried comparing the Oura’s heart rate variability measurements with those of the emWave2, and I couldn’t see much correlation. I’m inclined to trust the emWave2 more, but I’m not aware of good evidence on the subject.<\/p>\n
The Oura also helps track exercise, at least for hiking (it doesn’t seem to do much for weightlifting, but most of my exercise comes from walking\/hiking). It reports slightly less calories burned than what I calculate from a cheap Garmin GPS and this calculator<\/a>. I’m unsure which of those 2 measures is more accurate. If I were only using the GPS to measure calories burned, I’d give up on the GPS, because the Oura doesn’t have problems such as poor reception, or me forgetting to turn it on or off at the start and end of a hike.<\/p>\n It said I slept 3 hours on a red eye flight. My subjective impression was that it was somewhat debatable whether any of that ought to be classified as sleep. But what do I know? I have some evidence that I can sleep without being aware of sleeping (mainly from people reporting that I was snoring, at a time when I thought I was awake and not snoring).<\/p>\n My ring isn’t quite the right size for my ring finger. I ordered it based on prior information about what ring size worked for me, rather than using Oura’s measuring procedure. I’ve ended up wearing on the middle segment of my middle finger instead. That’s works well enough that the difference seems unimportant.<\/p>\n