Exercise is physical activity that requires planned structured repetitive movement. Fitness is the the body's ability to supply energy during continuous physical activities.
One of the signs that sleep is necessary is that all living creatures are harmed by lack of sleep. Correct answer: A Sleep serves important evolutionary functions for all animals, because sleep helps animals consolidate memories and learn. Animals sleep according to how much they eat – animals that eat food with a lower caloric density sleep less than others. However, lack of sleep and if the deprivation is long enough it can kill animals.
