Why the monastic hours were less punitive than I imagined

WhenI first discovered that the seven monsatic hours of prayer included a prayer time that interrupted sleep, I used to feel that this was surely part of a punishing ascetic schedule. Now I'm not so sure. Evidence has been accumulating that we humans may, in fact not only be wired to have two roughly 4-hour sleep periods separated by an hour or so but that reading historical evidences shows that until the industrial revolution, most people seemed to do just that.
 "For most of evolution we slept a certain way," says sleep psychologist Gregg Jacobs. "Waking up during the night is part of normal human physiology."
One of the things that some texts mention is that some people used this time for spiritual practice. So it seems to me likely that the monastic offices were merely a monkly or nunly version of this.
BBC News - The myth of the eight-hour sleep: