What the above commenter said is generally good advice, but I would add on limiting your social media intake. Finding an online community to interact with (with voice or video chat kinds of things involved) is a better use of online time. For the coding, you could try moving that to the morning, and socialize in the afternoon/evening, and that will help you get on a more normalized schedule. If your leisure time is spent mostly with other people, it's a lot easier to sign off and go to bed when everyone else does as well.

Edit: Also throw in a multivitamin and 2000-5000IU of Vitamin D3 because nutritional deficiencies can cause psych problems as well as exacerbate or prolong said psych problems.