Can adults adapt to less sleep? I am asking whether adults, especially in circumstances like a monastery or Zen center, can become able long-term to sleep only about 4 to 5 hours a night? So, that would mean: no children to care for, no heavy labor, lots of time spent meditating and doing other things that the body would find restful and undemanding...

Can the mind get along on much less hours of sleep than the usual adult? I am not asking about the absolute numbers, only if it can be reduced and sustained over years, or permanently?
A paper by Kaul et al. from 2010 suggest that meditation can indeed decrease the need for sleep. Meditation acutely improves psychomotor vigilance, and may decrease sleep need

Quote from conclusions:


  These results suggest that meditation provides at least a short-term performance improvement even in novice meditators. In long term meditators, multiple hours spent in meditation are associated with a significant decrease in total sleep time when compared with age and sex matched controls who did not meditate. Whether meditation can actually replace a portion of sleep or pay-off sleep debt is under further investigation.