Some people actually are short-sleepers naturally. He might be one of them. Or he might just be perpetually exhausted to the point where he's learned to "function" on less sleep.
Speaking from personal experience, you can get used to 4-5 hours a night and think you're okay. Starting getting north of 7 and you will notice a difference after a week. (Unless you're a short sleeper, I suppose they just can't sleep that much.)
Some do get by on very little sleep and claim to be able to functionally do so. However, there is a growing body of evidence to indicate that this has serious long term health effects and may contribute to dimentia later in life.
He can't, unless he has a beneficial genetic mutation that makes his sleep super effective.
He needs to hire a delivery driver, record the hockey games on a DVR to watch the next day, and buy blackout curtains for his bedroom, so he can go to sleep by 5 PM.
Fine. He should get a sleep study done, so a specialist doctor can describe the damage he is doing to himself, scare him a little, and come up with a treatment plan from there. If you only sleep for 4 or 5 hours a night, you are killing yourself.
Everybody who does odd-hours work should have a sleep specialist doctor, and this guy is one of the few who need one, that can actually afford one. Sleep is important. It is not wasted time; it is biologically necessary.
Speaking from personal experience, you can get used to 4-5 hours a night and think you're okay. Starting getting north of 7 and you will notice a difference after a week. (Unless you're a short sleeper, I suppose they just can't sleep that much.)