Were they able to wear them all in the correct location, or were a few in the wrong location because how do you wear that many watches? Also, it's only one journo over one night. Statistically insignificant.
This isn't my issue with sleep monitoring. My issue is that I can have a great night of sleep, only for my monitor to tell me it 'scored 40/100' and that makes me feel like crap for the day. Or I have a bad night sleep and it scores me '82/100' and I don't trust it.
Sometimes you can have too much data. In 2026, all I do is sleep. No monitoring.
A journalist wore 4 wearables simultaneously and compared them to an in-lab sleep study.
The winner?
Apple Watch matched total sleep time to the minute and had the closest agreement with the lab sleep-stage results.
They all overestimated deep sleep.