As a person sleeps, it is thought that the brain performs vital housekeeping tasks, such as organizing long-term memory, integrating new information, and repairing and renewing tissue, nerve cells and other biochemicals. Sleep allows the body to rest and the mind to sort out past, present, and future activities and feelings. Nearly every animal sleeps to some degree. Thus, it only makes sense that predators sleep more than animals that are prey. For humans, the amount and quality of sleep achieved is directly proportional to the amount and quality of the next day's productivity.
Sleep is a necessary and vital biological function.
It is essential to a person's physical and emotional well being. Studies have shown that without enough sleep, a person's ability to perform even simple tasks declines dramatically. The average sleep-deprived individual may experience impaired performance, irritability, lack of concentration, and daytime drowsiness. They are less alert, attentive, and unable to concentrate effectively. Additionally, because sleep is linked to restorative processes in the immune system, sleep deprivation in a normal adult causes a biological response similar to the body fighting off an infection.