Monks work, a lot, both in order to maintain the monastery itself and to produce goods for the outside community.
You can easily see this for yourself in Eastern Europe: except for a few highly touristic sites, you are generally welcome to stay at a monastery for a time without being asked to pay anything, but you will be expected to assist the monks in the work they do each day. The work – from chopping wood to weeding gardens – is exhausting. It is a mystery to me how the monks manage to keep up with everything and maintain a very positive attitude, all on 4 hours of sleep a night and diet that is fasting half the year.
not sure where you got 4 hours of sleep. Monks generally wake up early but they also retire early.
For example: http://www.stmarysmonastery.org/daily_life.html wake at 4:35, retire (though not necessarily sleep) at 20:15. The schedule has about 6~7h of work tops:
* following Mass + Terce + community meeting of 0930 (so probably about 1000~1015) until 1300
* following the Office of Nones (which starts at 1500) until 1800, and that can also be studies
Unlike mental exhaustion, physical exhaustion makes it very easy to fall asleep and sleep deeply. This is the real secret to the monks' success. Those of us who tax our minds with knowledge work don't get the benefits of physical exertion that the monks enjoy.
This is not to say the monks didn't work or didn't follow ascetic regimens, but they weren't doing all the work of keeping the monastery running.