It sounds like you are concerned about his drinking.

Maybe something happened in the past that sends up your radar.
It may be worth downloading some Adult Children of Alcoholics lit on a tablet so you can see it but nobody else can.

If he is not harming anyone, or himself, can you address the feelings he's having (stress) and ask how you can offer support?
A non-drinker who takes a sleep aid is just a different generation of person medicating. Some people find alcohol more accessible and less stigmatizing as a sleep aid.

Just check in with him about the feelings, not the behavior.
Check in with yourself re: why it bugs you.