When you take away sleep, the brain becomes unstable. You can't pay attention, you have trouble sustaining activities over time. Some people show it right away, while other people can go quite a while without showing it.

That's one of the reasons some people avoid napping altogether.

Uncontrolled or covert napping, however, is still probably very common. One need only move through a building surreptitiously and peek at people to find some subset of sleep at any given time.

If people suffer from insomnia, they should avoid napping unless their sleep doc says it's OK.

My sense is that planned, permitted, endorsed napping by management is still rare.