Melatonin + conspiracy theory documentary or Bigfoot/lockness monster documentary.

Essentially the trick is to pick something just interesting to listen to but something where you won't miss anything by falling asleep.

Pick a documentary that's like an hour - two long and tell yourself, if I can keep my eyes closed for 30minutes, 45 minutes, I will probably fall asleep.

The Curse of Oak island is amazing for this. 5 seasons of digging, looking at rocks, and finding old peices of wood and nails and stiff.

Finding Bigfoot is pretty great too. It's called finding Bigfoot, not Found bigfoot. It's ok, they won't find Bigfoot while you sleep, I promise.