Sleep
The CAA frowns on all pills, because no long term trials have ever been carried out.
I used to use Temazepam 10mg or 20mg, which were used by RAF crews during the Falklands war, with good effect. Prescription only, and doctors not too keen on giving them out.
Then very occasionally I tried Dormicum 15mg. Also prescription only
If you're in Europe you can buy 25mg Doxylaminsuccinate over the counter. But not in UK. This is an antihistamine rather than a sleeping pill, but it did help for the occasional sleeplessness.