There may be people who can shift their night cycle, maybe even because of genetics or circumstance, but medical science says that circadian rhythms are hard to

There may be people who can shift their night cycle, maybe even because of genetics or circumstance, but medical science says that circadian rhythms are hard to change and changing sleep cycles too fast leads to issues. And this may also be a case of how many problems you have. Night shifts might not be a problem on its own, but throw in a little depression, or getting overweight, or whatever, and it's going to suck big time.