The hypothalamus is one of the evolutionarily oldest, yet smallest, parts of the brain. However, its importance is highlighted by the fact that it controls basic life functions such as: energy metabolism, feeding behavior, energy expenditure, electrolyte and fluid balance, thermoregulation, wake and sleep cycles, sexual and parenting behaviors, and is critical for maintaining homeostasis within the body. The hypothalamus is a main relay station between the peripheral and central nervous systems as it receives sensory input from the body and helps the brain respond appropriately.