melatonin
(MEH-luh-TOH-nin)
A hormone made by the pineal gland (tiny organ near the center of the brain). Melatonin helps control the body’s sleep cycle, and is an antioxidant. It is also made in the laboratory and sold as a supplement.
The NIH Clinical Center (the research hospital of NIH) is open. For more details about its operating status, please visit cc.nih.gov.
Updates regarding government operating status and resumption of normal operations can be found at opm.gov.