I used to find the first generation Apple AirPods to be quite good. For me, they sat relatively flush in my ear, so falling asleep with them in wasn't uncomfortable, and they'd be just loose enough to gently fall out without me noticing once asleep.

The latest gen don't work as well (for sleep) as their shape is slightly different (more "bulbous" perhaps) and are much more uncomfortable to fall asleep with in my opinion.

As to how wise it is to sleep with tiny bluetooth transmitters inside your skull... that's a different question.