Sleep is extremely important to human health and well-being. Humans and animals need sleep in order for their bodies to be prepared for the next day. Everyday activities, one’s appearance, and how one expresses oneself all rely on this necessity. If one is tired (from not getting enough sleep), one will not be able to function properly in common activities. Being sleep-deprived leads to struggling to remember information, altering one’s mood, health, and a number of other effects. Sleep deprivation (not allowing a person enough sleep) can even be used as torture. Also, the immune system releases compounds known as cytokines which are used to help fight inflammation and infection. If a person does not receive enough sleep, they will not have enough cytokines to protect them from getting sick. The body may not have time to complete memory recollection, muscle repair, and release hormones that regulate growth and appetite.