In Watch OS, sleep tracking can be turned on as part of the watch. You can set up your sleep tracking in the Apple Health app by specifying your sleep focus times.
Then in the morning when you wake up, the sleep (and associated heart rate data).
The oura ring is also a good device, especially built to track sleep. Even if you have an Apple Watch, it can add a bit of additional HRV data (sampling every 5 minutes) rather than every couple hours.
You can connect the Oura integration in settings to load HRV data directly from them (since it isn't synced to HealthKit) — the rest of the data like sleep segments comes through Apple Health automatically.
However, there can be a few hours of delay in syncing the HRV to Oura servers and then to Gyroscope, so you should check your final sleep score in the mid day. If you are using Oura, you may want to switch from Sleep Score Ultra (which syncs instantly when you wake up) to Sleep Score Classic (which happens in the background and allows for more time to sync).
Other devices like Fitbit will also sync sleep to Gyroscope, though with less detail.
No devices? You can still track sleep time
If you don’t have any of these recommended sleep trackers (and are just using RescueTime on your computer and Gyroscope on your phone), that is fine — there are still a lot of options.
In iOS14+, the phone has its own sleep tracker that is built into the alarm clock. It is not always accurate, though, so will need frequent review as well to make sure only correct data is saved!
You can also use the built in Sleep AI to start detecting your sleep based on gaps in your other data. To do this, simply open each day's daily report and you will see our estimated sleep detection if available. Then customize or save it to add the sleep to your account.
Since it is missing the resting heart rate data, the sleep score won't be as nuanced — but your bedtime and sleep duration is still valuable data and better than nothing.
If none of those detect your sleep, you can always add it directly into the app from the + button. From there, you can enter in the start and end times to save it.