I worked an overnight shift for about a year.
The hours were 6pm to 5:30am. This was a 7 days on / 7 days off shift.
My sleep schedule used to get so screwed up on my 7 day on shifts, that sometimes, during my 7 days off I'd pass out and sleep about 24 hours straight when I was done with the work. Then I would stay awake for 2 to 3 days with no sleep, then sleep 12+ hours, then awake for 24+ hours etc .....
The worst week that I can remember, I got home Monday AM at 6am. I went online, had a snack, watched TV, etc for a couple of hours. I then went to sleep, it was about 9am. I woke up at 3am on Tuesday. Tuesday I didn't sleep at all after that. Wednesday I looked online for a car, but didn't really find anything that totally struck my eyes (I was also somewhat indecisive as to what I really wanted, and how much I was willing to pay.) After 3 or 4 hours of research and price shopping, I was tired of that, so I went to play play Wolfenstein Enemy Territory. I did not sleep at all Wednesday. Thursday I continued to play ET until about 9 or 10 am, then I had some food, went grocery shopping, ran to the bank, mailed in bills, etc. By the time I was done doing errands, it was mid afternoon, I did not want to sleep in the afternoon since I had plans that evening, and I knew that if I fell asleep, there would be no waking me. That evening I went to a friends house for a few hours, we played some cards. It started to get late, I was tired, so I drove home, it was about 11pm now. Once home, I watched the history channel or comedy central (I can't really remember, this was about 3 years ago), I decided to drink a pot of strong coffee, I no longer felt tired. Come about 3am ... the infomercials show up, I switch to the conan rerun on NBC and watch until about 4 am. Then I play some more ET. By 8am ... I'm tired but decide to have some more coffee. I played around on cars.com for a good 2 or 3 hours doing different searches until I finally found exactly what I wanted for a price I was willing to pay. (a 1999 Chrysler 300M I drove to the dealership, signed papers for a couple of hours, and finally made it back home by about 7pm. I was dead tired, however, I did NOT want to go to sleep at night, since that would further screw up my sleep schedule during my work week, and I was not about to do that. I drank another pot of coffee and ate a BUNCH of penguin mints (think altoids with caffeine). I played Wolfenstein ET until about 3am, but my mind was totally unable to function. I was no longer coming in first place, and I was about to collapse. I went to my bed, and passed out.
After that 90+ hour marathon, I vowed to change my schedule and NEVER do anything that stupid ever again.
Since then I've had a couple of sweet 4 x 10 hour day schedules, and currently a 5 day M-F schedule. I would never go back to overnights, as I don't think I could deal with it any more.
Cliffs .... Overnight schedule at work screwwed up my head. I did a 90+ hour no sleep marathon back in 2002. I Antirecommend this practice!