In Monasteries and other spiritual contexts, there seems to be a "rule" that sleep is wasted time, and so the usual daily schedule only allows for about 4-5 hours of sleep. This might be enough for an 80-year-old, but anyone else will probably be sleep-deprived and not very functional, let alone be able to make any spiritual progress.
I asked about whether adults can get by with less sleep, and got no answers. Does anyone know why spiritual scenarios seem to try to reduce sleep hours? One thought is that people think it is associated with laziness, indolence, lethargy, unproductive time, idleness, sloth, etc. But no one tries to reduce food intake, or use of the toilet, so why is sleep the big bad guy?