Smoking to fall asleep: how big of a sin is this

Salaam ou aleikom wa rahmatou Allah ie wa barakatahou my dear brothers,

First of all my apologies for my question, but recently I have had some troubles with sleeping, and I think this might be due to magic, or jinn, but I’m not 100 percent sure.

However smoking a cigarette (even though I stopped) helps me relax and fall asleep, I understand that this is not good and that this is a sin, however, my question is more related to how big the sin is, might this be a form of shirk because the means are not following correct and is even a sin? By the way I habitually always make my dua and my dhikr to try and fall asleep, and sometimes it helps sometimes it doesn’t…Jazak’oum Allah ou khayran.

Muhammed