Vertebrate brain
The hypothalamus is a small region at the base of the forebrain. It is the central control station for sleep/wake cycles, control of eating and drinking, control of hormone release, and many other functions. It sits immediately above the pituitary gland, and secretes hormones into the gland. These hormones inhibit or stimulate the pituitary gland. The gland, in turn, makes hormones which affect the rest of the body.