All posts tagged sleep


I’ve been using an Oura sleep tracking ring for six months.

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.

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.

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.

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.

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.

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.

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. 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.

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).

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.

See this comparison with several alternatives for a more detailed analysis.

Mostly, the Oura simply reassured me that I don’t have significant sleep problems, other than the times when it’s obvious that I took too long to fall asleep, or woke up too early. I suspect that the Oura would have been moderately valuable if I had had sleep problems that were hard for me to detect.

Sleep Improvements

I’ve made several changes over the past few months that have improved my sleep.

A cool environment is important to my sleep, and Chili Pad has proven to be a better way to cool myself on warm nights than attempts at air conditioning. I have it pump water at 72 or 73 degrees through small tubes sitting between me and the mattress. I was careful to buy enough tubes to put the pump in the next room where its noise and light aren’t noticeable. One drawback is that the straps that should hold it in place no the mattress weren’t quite the right length, and broke immediately – that creates a minor problem where it slides around a bit.

The second change was to use only lighting with no blue light an hour before going to bed. I had tried this more than a year ago by placing a red filter in front of my computer monitor and turning off most of the regular lighting. That produced little change even though it cut out 90 to 95% of the blue light. Last week I bought a red light to replace the remaining regular lighting, and now I see a moderate improvement in how quickly I can fall asleep.

I’ve started occasionally using a sleep mask so that I can sleep a bit later than sunrise instead of letting the sun completely control when I wake up. But I don’t like the way it feels, so I won’t use it often.

I’ve also started using a Zeo, and intend to measure the effects of caffeine on my sleep. But I don’t like wearing the headband, so I won’t use the Zeo for long periods of time.

Book review: Counting Sheep: The Science and Pleasures of Sleep and Dreams by Paul Martin.
This book makes convincing claims that most people give too little thought to an activity that occupies a large fraction of our life.
It has lots of little pieces of information which can be read as independent essays. Here are some claims I found interesting:

  • “sleepiness is responsible for far more deaths on the roads than alcohol or drugs”.
  • Tired people rate their abilities higher than people who slept well do.
  • Poor sleep contributes to poor health a good deal more than medical diagnoses suggest, but hospitals are designed in ways that hinder patients’ sleep.
  • Idle time was apparently a status symbol up to a century ago, now being busy is a status symbol. This should have economic implications that someone ought to explore in depth.
  • People in a vegetative state have REM sleep. This sounds like cause to re-evaluate the label we apply to that state.

While the book has many references, it doesn’t connect specific claims to references, and I’m sometimes left wondering why I should believe a claim. How can boredom be a modern concept? When he says “no person has ever gone completely without sleep for more than a few days”, how does he know he can dismiss people who claim to have not slept for years?