A great rest at night enables you to have a good, productive day of work. Life is a cycle of effort and rest. The effectiveness of each depends on the other. You cannot cheat this cycle. Sleep all night and day and you'll feel awful.
Maximum effectiveness requires balance.
You've got to work hard, and you've got to stop along the way to rest and relax. Sometimes you can be more effective in your work, by doing less of it. Sometimes you can get a better rest, when you work a little harder. Try to drive your car with only three tires, and you'll appreciate the need for balance. Get out of balance, and nothing works right.