The hypothalamus is a small part of the brain near the brainstem of all vertebrates that produces the hormones responsible for major body functions of the autonomic nervous system such as sleep, hunger and thirst, sex, emotions and temperature regulation. (One of the main functions of the hypothalamus is controlling hunger and regulating the body’s metabolism.) The hypothalamus regulates these functions in response to cues it has received from outside stimuli, such as light, smell, electricity and chemicals released in other parts of the body. Located just below the thalamus gland, the hypothalamus also controls the actions, especially during stressful situations, of the pituitary gland. The pituitary gland, or “master gland,” helps connect the body’s central nervous system to the endocrine system and controls the thyroid and adrenal glands, as well as the testis and ovaries. When the hypothalamus is not functioning properly, the most common side effect is that it fails to produce the hormones necessary for particular body functions. Given that the hypothalamus controls the pituitary gland, damage to the hypothalamus can have severe repercussions for the body’s endocrine system as a whole.