There are NO products in the world that can guarantee you sleeping... Not including things that actually just knock you out, as those does not help the quality of your sleep, not to mention the many bad side effects they invariably have.
Scents, oils, bathbombs, crystals, etc. Those might have effects for various individuals, but that had never been any confirmed & repeatable researches, that are not funded by the product makers themselves that link them directly with the effect of sleeping; Most of them have to do with placebo effects that, well, you would get the same effects whatever you use as long as you "believe" that it will work.
And placebo effects are probably in at least half of everything we do in our lives, in one way or the other.
I wouldn't say it won't work. Hey, he might be the person with the exact type of triggers that make it 200% more effective than average, and if that's the case heck yeah go for it.
But it'd be hard for me to recommend any specific thing though. (In my line of work it would feel kinda... Irresponsible? Especially if people have to pay money for it, when my clients are usually the types that will have problems buying a pair of $20CDN shoes.) Even the things I've said were just mostly repeats of what the specialist I saw last week said, and all of them can fail to work on any other people but me really.