I had heard Whoop was supposed to be excellent for sleep tracking, so I started using it alongside my Garmin. I’ve worn it for three weeks now. The first unit was accurate maybe one out of seven nights—never two nights in a row. I assumed it was defective, so I bought a replacement. The second one has only been accurate about two out of seven nights.
I’ve worn it exactly as instructed, even placing it on my arm one day longer than I did with the first device. Last night it showed me going to bed 2.25 hours later than I actually fell asleep. Meanwhile, my Garmin is almost dead-on every night. I end up manually correcting the data.
The analytics look impressive—if they were reliable. I’m using it because my trainer recommended it, so I’ll stick with it until that’s finished. But based on my experience, the sleep tracking is simply not very good. Hopefully you will fix it or people will figure out that it is not that great of a device.