During photosynthesis, light energy is used to produce ATP molecules which are then used to construct sugar molecules from carbon dioxide and hydrogen obtained from water. Chloroplasts have two outer membranes and several stacks of small disc-shaped membranes called thylakoids (also spelled thylacoids) inside.
Scheduling a week off will give your body time to do this and will also help you return to your workout stronger and ready to challenge your body once again. Many endurance athletes end their season with a week off and many weightlifters will take a week off from their program every four to eight weeks.
Really, there are no set time periods, a lot of your rest periods depend on your body type. The average person (if there is such a thing) should do something like three days on one day off, with about 12 hrs between workouts on your days on. However, I know some powerlifters who work out every other day, 1-on-1-off. Ultimately, you need to find your routine that best compliments your body.