I work the night shift (2230-0700) and when I am not working I keep night shift hours, rarely going to bed before 0200, mostly off to bed between 0300 and 0600.
When you are young to can get away with, for awhile, shifting your shifts, but as you get older, the harder it gets, unless you are one of those who can get by with little sleep.
If you are going to shift to essentially a night life, it will take a while, but you need to be consistent and you need to find consistent times to get up and go to bed. At first you will experience "sleep hell" aka jet lag and that could go for a month. Do some reading about Melatonin, which can help with the shift of sleeping hours so radically. Melatonin can be gotten at any pharmacy, but use it carefully.
Use bright lights in your living quarters and use as many full spectrum lights as possible.When you get up, spend time outdoors in the sunlight, if possible. Trying to function in a dimly lit living/work environment will make things very difficult, but when sleeping, keep you room as dark as possible, using only very dim light if you have to get up.
As for sitting meditation, do it in a brightly lit room, eyes open if you are having difficulty staying awake. Also, do lots of walking or standing meditation.
Eat regularly at the same times as much as possible and exercise.
And keep in mind that doctor appointments and the like are going to be on the day shift, get them as early as possible or as late as possible.
And finally make sure you sleep at least 8 hours, even if you have to do it 4 here and 4 there, but best to try to do a solid 8 hours straigtht, and keep away from sleeping aids. It is not that you can't use them. It is, rather, they present a problem of dependency and messing up you dream/sleep cycles. Anything else, ask.