I currently work a 2day 2night 4off rotation in a NeoNatal ICU. I will run after my shift on the first day, before I nap before the first night and on at least 2 of my days off. It is possible to run after a 12 hour shift, I find I sleep better. I go home, eat a light snack, do some yoga to warm up and then do a light and easy run, usually about 5-7km. I also go all out on that run before my first night shift, it is usually my middle distance around 8-11km. I then go home, do some stretching, eat a light snack and a cup of sleepy time tea, read a bit and am happily ready for a nap around 2. Keep running, it is the one thing that will keep you sane and make you feel less like you are cheers!!!