Melatonin is a hormone produced by the pineal gland, a small, pine cone-shaped endocrine gland located deep within the center of the brain. Melatonin is secreted at night and regulates your body's day/night cycle, also referred to as circadian or biorhythms. Melatonin deprivation may occur from prolonged periods of too little sleep or night shift work, which upsets the normal day/night cycle. Some detrimental health effects are thought to result from low melatonin levels.
Melatonin deprivation may speed the rate of brain aging, according to the University of Maryland Medical Center. Levels of melatonin are highest in young children and diminish as we age. Some experts think that low melatonin levels may be a contributing factor in sleep problems that some older adults experience, though this theory remains controversial. Melatonin also exerts strong antioxidant effects, implying that a lack of melatonin may result in oxidative stress within the brain that might be detrimental to brain function. There is currently no recommended dose for melatonin, and some people are more sensitive to it and require lower doses than others. Taking a higher dose than you need may cause anxiety and irritability. Melatonin has also been known to interact with blood pressure and antidepressant medications.
Melatonin deprivation may raise blood pressure and lead to kidney damage, according to a study published in the November 2010 issue of the "Journal of Pineal Research." In this study, laboratory animals consumed drinking water with 0.01 percent melatonin for 8 weeks. Blood pressure in the study animals was lower than in a control group that did not receive melatonin. Melatonin also reduced oxidative damage to the kidneys and promoted lower levels of urea -- a waste product of protein metabolism.
Seasonal Affective Disorder
The Harvard Health Publications newsletter reported that Seasonal Affective Disorder, also referred to as S.A.D. -- a condition associated with depression that waxes and wanes with the seasons of the year -- may be a result of low melatonin levels. People with S.A.D. tend to have an altered schedule of melatonin release, with the majority releasing melatonin at a later stage of the sleep cycle than people without S.A.D., and some who release melatonin earlier. The result, in each case, is an asynchronous sleep cycle that can lead to symptoms of depression, and, in some cases, bipolar disorder, schizophrenia or eating disorders.
A study published in the "Scandinavian Journal of Work and Environmental Health" reported that night shift workers may be more susceptible to cancer due to hormonal imbalances from upset of normal circadian rhythms -- the biological clock mechanism that coordinates the body's rest and activity periods to day and night cycles. Multiple endocrine changes, including melatonin deprivation, occur from night shift work, say the researchers, and these effects may contribute to promotion of breast and prostate cancers in some people.
- "Scandinavian Journal of Work and Environmental Health"; Shift Work and Cancer -- Considerations on Rationale, Mechanisms and Epidemiology; G. Costa et al.; March 2010
- "Genes to Cells"; Loss of Circadian Rhythm and Light-Induced Suppression of Pineal Melatonin Levels in Cry One and Cry Two Double Deficient Mice; Y. Yamanaka et al.; October 2010
- "Journal of Pineal Research"; Melatonin Prevents Hypertension and Increased Asymmetric Dimethylarginine in Young Spontaneous Hypertensive Rats; Y.L. Tain et al.; November 2010
- University of Maryland Medical Center: Melatonin