Apple

In short you don’t. If the sleep is less than 4 hours it doesn’t record. I switched to AutoSleep a few weeks ago and am really liking it.

Thats pretty much the only reason I stayed with fitbit, because I can sleep at random times and it will still track my sleep

AutoSleep. Once you ignore a lot of the derived data, and just look at actual measurements, it’s quite good. It’s also an affordable one time purchase, so no subscription fee for something pretty straightforward. It will also display the nighttime sleep data from the Health app, so you can even review that in app, and if confusing results are noticed, the comparison right in the same app is handy for me.