For some it is the best possible work arrangement, but for others it is hell on earth, a nightmare, the complete renunciation of any social life, a formula for marital splits and a deviation from natural biorhythms threatening to both physical and mental health.
I'm talking about the nightshift, of course.
US Bureau of Labour Statistics figures show 93,000 computer operators out of a total of 625,000 working on the night shift--around 15% of computer operators.
Mark O'Leary is an IT shift manager at Greenlane Hospital and has been working shifts for as long as he's been a computer operator.
"We do rotating shifts, so I do days and nights," says O'Leary. "I think it's called the Marks and Spencer system, we do 12-hour shifts--four days on, two off; three nights on, two off; three days on, two off; four nights on, eight off.
"Everyone likes the eight day break every four weeks."
To many that would seem an almost impossible routine. What about a social life?
"That was a problem when I was younger," O'Leary says. "I'm 34 now and married with two kids. When I was younger your Friday and Saturday nights were important."
O'Leary agrees to some extent that night-shift workers are isolated from the usual office routines.
"We've just had a Christmas function and I don't think a lot of the operators went--although I wanted to go but I couldn't because I was working.
"I think operations as a group tend not to join in with whatever is happening in the building. We get on day-to-day with them, though."
Family concerns are often raised as a reason against shift work and in the US studies show that many shift-workers are either single or divorced. But O'Leary doesn't see it as a problem.
"It suits me because I find I tend to see more of my family. There are blocks when I don't see them much at all, but then there are periods when I'm spending a lot of time with them."
O'Leary emphasises the benefits of a shift-work lifestyle, including the extra money paid for night work.
"The money's still there for doing shift work," he says, "though that's kind of fading out as a whole in New Zealand. I can see a day when working the middle of Monday morning will be no different from working Sunday nights.
"There are some people who prefer working nights over working days. I know people who don't like being around in the day, don't like wearing ties.
"When we're here we sort of have the run of the place. It's a lot more casual."
And is there any time to sleep on the job?
"No. It's too busy for that."
To O'Leary the question of who can work shifts comes down to a simple equation:
"If you can sleep during the day you can work shifts. If you can't sleep during the day you can't."