how important is sleep?
<answer> 1 Sleep enables the body and mind to rejuvenate, re-energize, and restore. 2 Sleep may have evolved as a protective adaptation-finding food in the daytime and hiding at night is easier. <context> Although researchers are not exactly sure why we need sleep, there are two basic theories: - 1  Sleep enables the body and mind to rejuvenate, re-energize, and restore. - 2  Sleep may have evolved as a protective adaptation-finding food in the daytime and hiding at night is easier.