For someone whose account is active 20 hours a day on a regular basis it's unlikely they're playing the game the whole time, they're doing a lot of idling (this was one way of earning the very high global time requirements before recent updates to the awards).
Someone calculated a while back that {TA}FireStorm was on for something like 95 hours over a five-day period for example. When you work it out that only allows for five hours per day for anything else you might think of. Now if we imagine that you could squeeze things like preparing food/beverages, going to the toilet, washing etc. into less than an hour that's still only about four-and-a-half hours of sleep per day, which is more than most people could manage and you sure as hell wouldn't be at 100% come the fourth or fifth day.