As I said, there is evidence that drinking alcohol regularly may cause PN. However, that does not mean that everyone who drinks regularly will develop PN. In particular, I don't think having one shot of vodka a night is likely to be the culprit. On the other hand, if you do not want to take the risk, it is certainly reasonable to stop drinking.
BTW, using alcohol as a medicine for sleep is considered a no-no. It actually may disturb your sleep later.
There is some evidence that medical marijuana may be helpful. I don't think you can buy marijuana online, but yo can buy various products counting mostly CBD. Google it.
Sorry for your discomfort.