I worked nights for 11 years. when i am single it is my favourite shift. The problem most people have is that they "pretend" to work nights but really are on a day schedule and work at night too...and complain that they are tired, duh.
A normal person wakes up, eats breakfast, goes to work for 8 hours, eats when they get home and then stays up for 8 hours, and sleeps for 8.
It doesnt matter when those hours start, as long as you keep that cycle.
You cant sleep right after work, or at the end of your shift it would be like very late at night for normal people, not optimal working time. You have to give up friends, family, and other expectations to keep sane on nights, and make them respect your schedule. If they call when you are sleeping, try calling them back at 3am for a chat and see if they like it. I found it really easy to go to the gym at seven am, right after work, since there was absolutely nothing to do and easy to get the workout in, it also prevented after work naps which are bad.