Melatonin & Circadian Rhythms

Melatonin is a hormone synthesized by the pineal gland.  It is produced from tryptophan, which is converted to 5-HTP, then to serotonin, then to N-acetylserotonin, and finally to melatonin.  Sheesh, that's a mouthful, isn't it?

Melatonin's primary role is to regulate the body's circadian rhythm, endocrine secretions, and sleep patterns, and natural melatonin production is directly influenced by day/night cycles.  Light inhibits melatonin secretion and darkness does the reverse (promoting melatonin secretion). 

Jet Lag & Enabling Sleep

Regulating the body's natural rhythms is why melatonin is so well known to world travelers, who move from time zone to time zone and must re-set their body's clock to achieve restful sleep.

Melatonin lowers alertness, body temperature, blood pressure, and performance for three to four hours after administration, enabling sleep.  The good news: There is rarely a "hangover" the following day! 

Melatonin is considered especially helpful for seniors with insomnia related to melatonin deficiency.

Seasonal Affective Disorder (SAD)

The pineal gland's ability to produce and regulate melatonin levels in the body is considered important for people affected by changes in moods during fall and winter. 

A part of the population is unable to effectively adjust their body rhythms to decreased exposure to daylight.  Those affected often alter find themselves craving carbohydrates, which appear to accelerate the production of serotonin, a precursor to melatonin.  

Boosting the Immune System

Melatonin is not as well known as an immune system booster, but there is a lot of interest in melatonin for its antioxidant, immunomodulatory, and oncostatic effects (reduced cell proliferation and reduced cellular transformations that are undesirable for optimum health). 

In one animal study, melatonin was 60 times more effective at preventing oxidative damage to cells than either vitamins C or E!

Melatonin, Endorphins & The Pleasure Response

Melatonin is gaining interest for a variety of other benefits, including heightening the effect of endorphins, the natural tranquilizers in the body that reduce pain and stress.

Along these lines, melatonin is being studied for its ability to:

• Reduce discomforts associated with normal menopause-related changes and improve moods in menopausal women. 
• Reduce the negative effects of stress-induced corticosteroids on the heart, arteries, bones, brain, and immune system, as well as on blood sugar.

Studies of melatonin are actually exploding, because this supplement has proven to offer a diverse set of benefits well beyond jet lag support!

Studies:

• HILL, S. and BLASK, D. (1988). Effects of the Pineal Hormone Melatonin in the Proliferation and Morphological Characteristics of Human Breast Cancer Cells (MCF-7) in Culture. Cancer Research, 48, 6121-6126.
• LISSIONI, P., MEREGALLI, S., FOSSATI, V., PAOLOROSSI, F., BARNI, S., TANCINI, G., FRIGERIO, F. (1994). A Randomized Study of Immunotherapy with Low-Dose Subcutaneous Interleukin-2 Plus Melatonin vs. Chemotherapy with Cisplatin and Etoposide as First Line Therapy for Advanced Non-Small Cell Lung Cancer. Tumori, 80, 464-467
• Lagneux C, Joyeux M, Demenge P, Ribuot C, Godin-Ribuot D. Protective effects of melatonin against ischemia-reperfusion injury in the isolated rat heart. Life Sci 2000; 66: 503-9.
• PANZER, A. and VILJOEN, M. (1997). The Validity of Melatonin as an oncostatic agent. J. Pineal Rsrch., 22, 184-202.
• Schernhammer, ES. Brigham and Women’s Hospital. June 4, 2003. Journal of the National Cancer Institute.  Possible link between nightshift work and colorectal cancer in women: Prolonged exposure to artificial light may be key trigger.
• Qi W, Reiter RJ, Tan DX, Garcia JJ, Karbownik M, Manchester LC, Calvo JR. Chromium(III)-induced 8-hydroxydeoxyguanosine in DNA and its reduction by antioxidants: comparative effects of melatonin, ascorbate, and vitamin E. Environ Health Perspect 2000; 108: 399-402.
• Zhang, Z., Inserra, P., Liang, B., Ardestani, S., Elliott, K., Molitor, M., and Watson, R. (1997). Melatonin, Immune Modulation and Aging Mini-Review. Autoimmunity, 26, 43-53.
• Cardinali DP, Brusco LI, Liberczuk C, Furio AM. The use of melatonin in Alzheimer's disease. Neuro Endocrinolpgy Letter - 2002 Apr. 23

Notes:

1. People should not drive or operate machinery for 4 to 5 hours after taking melatonin. 
2. Melatonin has sometimes made dysphoria in depressed patients worse.
3. Melatonin can reverse the negative effects of propranolol (inderal) and atenolol (Tenormin), but not carvedilol (Coreg), on nocturnal sleep. 
4. Use of melatonin with other sedatives such as alcohol, benzodiazepines, etc. may increase levels of sedation. 
5. Melatonin can stimulate immune function and might interfere with immunosuppressive therapy. 
6. Melatonin may increase human growth hormone serum levels and test results.
7. Melatonin use in some children with seizure disorders may lead to increased seizure activity. Those with seizure disorders should avoid melatonin supplements.
8. Aspirin and other NSAIDs, caffeine, or beta blockers may all lead to decreased melatonin levels.