God has designed our bodies to take a break. Engaging in one activity for long periods of time without a change of pace would kill us -- sinful world or not. During the French Revolution, one of the "amendments" made was a ten-day week. In other words, the people would have their normal routine of work and studies for nine days, and then a grand celebration with feasting and drunkenness would have its commencement on the tenth day. Just think of it: nine days . Naturally, they wore out. The fact is, our bodies need a more frequent and consistent resting time. That is why we should go to sleep and wake up at the same time everyday. Our body has a clock, and it needs to be heeded. At the Creation, God instituted measurements for time -- since, until then, there was no need for time; for "the earth was without form, and void." He made day : from one sunset to next one. He made the month : from one new moon to the next...