Looking for short-term and long-term solutions, and particularly interested in how to go to bed early.

First, decide why you consider it an addiction.  Then, change your mental attitude about that.   Poof!  You no longer think of it as an addiction.

Try to understand what parts of your MD activity you no longer enjoy to do but you are still doing, and start by changing that. 

Set yourself only fixed hours and time intervals you wish to be around, and whatever happens simply don't come here outside those intervals.

If you wish to quit entirely, close up lose ends, decide what people you still want to be in contact with and keep a different communication channel with them (like facebook, discord, email).

I knew many people that at some point decided to leave, but a year or two later decided they want to return, so my advice is to GRACEFULLY leave and don't do a mess behind you.