lol three hours before work and time to exercise and still worrying about being tired, you guys are needy.
I have 5 kids. My night blocks were 630p-8a usually, run home help wife get 3 kids ready for school, drive kids in, get back home around 9-930, help feed/change the two littler ones, let wife take an hour or two nap (who was up most all of the night feeding, changing and rocking kids who are germ machines and always sick), eat something, take a shower, go back in and pick up the younger kid who only goes to half day school, get home and finally go to bed around 1-130p. Wake up around 330 to feed the screaming newborn while wife has gone to pick up the two older kids from school, go back to sleep, wake up at 530 to eat dinner, spend 30 min or so with the kids and then head off to work.
In 6 full months of nights (6 - 4 week rotations of sun-fri nights) over 2 1/2 years I may have gotten >5 hours of sleep 6 times. And Fridays you go to clinic after the night shift.
Long story short, just do it. It's not a big deal. Go to work. Go home and sleep. Get up and do it again. You will do fine. Because you don't have a choice. In general I have found month long night blocks are a million times easier on your body than doing something asinine like q5 call with. 24-30 hour shift every fifth day. I love night blocks. Don't sweat it it's not going to be nearly as big a deal on your body as you think.
If you think about it, getting up at 530 for hospital ward months, working till like 8pm for twelve straight out of every 14 is so many more hours and so much more wear on your mind and body. Night blocks are awesome in comparison