Yep it's a regulation fast. Clears throat and assumes best Cliff Claven posture... At night they will grow, using the sugars they stored during the day. Another fact, is that during the night they will use just about as much oxygen as they produced during the day. The o2 is used to burn the sugars they produced. When the night temps are low, like they are in northern states, they don't use much energy though. That is why sugar beats and potatoes thrive in northern climes.