A good number of years ago (somewhere between 20 and 25), I worked for the company which maintained the ticketing system on Melbourne's public transport system, known as Metcard. I was on the 'graveyard' shift from 10 pm. till 6 am. The job involved taking calls from the various companies, Metrail, Yarra Trams and numerous bus companies, who were reporting problems with the ticket issuing machines or gate validators, recording the details in a database, from which the engineering dept despatched maintenance crews to fix the problems. I also monitored burglar alarms on the railway station ticket vending machines which were regularly broken into overnight, and reporting to Chubb Security who despatched guards to try and catch the villains or guard the machines till a maintenance crew could arrive. This meant sleeping through the day, driving into near the city where my wife worked, picking her up and driving her home, eating with her and the kids, then heading off to work. During the quiet hours, I had a supply of letters to people who had lost money in the machines or had their tickets destroyed in validators, into which I had to put replacement tickets, to be posted by the dayshift staff. Finishing at 6 am, driving home to collect my wife and driving her to work, then returning home to sleep.
I did this for about 18 months, working as a temp through a temp employment agency. It certainly does play havoc with your circadian rhythm.