Finding the Best Sleep Tracker

Earlier this year, Andrej Karpathy wrote an in-depth analysis of four sleep tracking methods that Federico recently recommended I read. I’m glad he did, Karpathy, an AI researcher who has worked at OpenAI and Tesla, took the kind of nerdy, data-driven approach that I love.

Over the course of two months, Karpathy plotted sleep tracking results from:

an Oura ring

a Whoop fitness band

an 8Sleep Pod 4 Ultra smart mattress cover

the Apple Watch running the app AutoSleep

Karpathy got the best results from the Whoop band and Oura ring, but just as interesting were how the data correlated to how he felt after a good night’s sleep:

…my sleep scores correlate strongly with the quality of work I am able to do that day. When my score is low, I lack agency, I lack courage, I lack creativity, I’m simply tired. When my sleep score is high, I can power through anything. On my best days, I can sit down and work through 14 hours and barely notice the passage of time. It’s not subtle.

I recommend reading the entire post for all the details of how each tracking method compared on variety of metrics. I’ve long been intrigued by the Whoop band and Oura ring as a companion to the Apple Watch. There’s overlap between the devices, but Karpathy has planted a seed in my brain that may lead to my own multi-device experiments.