Guides
The background you need before buying anything: what trackers measure well, what they do not, and how to read the numbers.
- Explainer
Sleep trackers agree on how long you slept. They disagree on how.
Before we test anything, here is what the published evidence says you can trust from a wearable, and what you should take with a pinch of salt.
Coming next: how to read HRV, what a sleep apnea notification does and does not mean, and the real cost of sleep-tracker subscriptions.