If theories that assert sleep is necessary for restoration and recovery from daily energetic demands are correct, what do you predict about the relationship that would exist between individuals' total sleep duration and their level of activity?

Any being, human, animal, plant or microbe, that requires sleep in order to regain the necessary strength and capacity to respond on a daily basis, and thus be more efficient in using energy to produce activity, would then require long periods of sleep, or longer periods of sleep, if they are going to have a longer period of activity. And conversely, those who have lower levels of activity will consequently need lesser periods of sleep in order to recover and restore their bodies.

Explanation:

Sleep is in fact the only efficient way in which the body can restore and recover itself from the activities of a daily routine, whatever these are. However, the more energetically demanding the activities, the more rest and restoration will the body require to regain its balance. When highly active people, or another species, spend more energy than time to rest and regain it, they become less efficient and their metabolisms will slow down. This is why there is a direct connection between periods of sleep and periods of activity.