Melatonin, Light and Circadian Cycles
Abstract
The body's circadian rhythms affect many aspects of human psychology, physiology, and performance. Melatonin, a hormone secreted by the pineal, is an important element of human circadian rhythmicity. Melatonin is normally at a low level during the day, with a pulse of secretion at night. The timing of melatonin secretion is controlled by the suprachiasmatic nuclei of the hypothalamus. The neuronal pathways which mediate this control are discussed. Light exposure is the main factor which adjusts the hypothalamic clock that controls melatonin release. Melatonin is altered in many disease states. It interacts with other endocrine systems. It probably plays a role in jet lag. Various drugs, including many that are commonly used and are likely to be taken by military personnel, can affect the melatonin system at different levels: by shifting the hypothalamic clock which controls melatonin release; by directly suppressing release at the level of the pineal, without altering the underlying rhythm; or by altering or blocking the effects of melatonin after it has been released.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 25, 1989
- Accession Number
- ADA223196
Entities
People
- Deborah Smith
- Paul Naitoh
- Tamsin L. Kelly
Organizations
- Naval Health Research Center