I struggled (and still do struggle to some degree) with sleep for a while.
Depending on how you’re coping now, I would suggest not adding more drugs to your system. If you can get 6 hours sleep, that’s not so bad.
I used to read before bed, dim the lights for an hour or two before, no screens, listen to a podcast or guided meditation if I was bored and to be honest they didn’t help much consistently, but at other times I felt they helped. So I would suggest trying those things, or any other good routines you are interested in that you may hear about here or elsewhere.
My sleep did get better, but I still have flare ups where I can tell I’m going to have a bad couple of days. I do get tired now, but didn’t.
It might be worth trying to get your sleep problems logged with your doctor now so that you can say you’re planning on trying various natural methods to help, but if nothing is improving or getting better then you’d like to try something to help. I assume and hope you’ve reported your problems with finasteride already.
If something is prescribed, I suggest you check here first before taking anything. I believe anti depressants are sometimes prescribed for sleep problems, which have brought people here.