"Well, think about it. The greatest menace in space is going coffin crazy. You are shut up for a long time in a small space and there is nothing outside but some mighty thin vacuum ... no street lights, no bowling alleys. Inside are the same old faces and you start hating them. So a smart captain makes sure you have something to keep you interested and tired - and ours is the smartest you'll find or he wouldn't be on this trip."I suppose that's the same problem faced by the abbot of a monastery - how to keep the crew from going coffin crazy and killing each other. Keep them interested with prayer & liturgy and keep them tired with manual labor, as discerned by St Benedict some 1500 years ago. Or maybe it's the other way around, come to think of it: keep them tired with liturgy and interested with stuff to work on.
Keeping them interested and tired is decent advice for parents, too.