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Melatonin

By Alan R. Gaby, M.D.

Melatonin is a hormone synthesized from tryptophan in the pineal gland and in the gastrointestinal tract. It’s involvement in moderating circadian rhythms and enhancing sleep is well-documented and some research indicates it also promotes immune function. Melatonin secretion may decline with advancing age. However, this decline does not appear to be a general characteristic of healthy aging but, rather, an effect of age-related health concerns or of certain medications.‡1

Much of the research on melatonin supplementation is focused on its potential to help promote normal sleep. It also appears to be useful for helping to reset the circadian clock after long airline flights across time zones.2 Because of these effects, melatonin has been used to support sleep for selected individuals, particularly those who are unable to fall asleep for an extended period of time after they go to bed.3,4 As little as 0.3 mg of melatonin taken at bedtime is often supportive, although larger doses of 2-5 mg have been used in most clinical trials.‡

At a dose of 3 mg at bedtime, melatonin has also been found to be supportive for women with gastrointestinal discomfort. In an 8 week double blind trial involving 34 women, melatonin supplementation provided statistically significant support for GI function and comfort.5‡

In another trial, melatonin was found to support macular health. It is believed to protect retinal pigment epithelium cells from oxidative damage, both by functioning as an antioxidant and by potentially moderating eye pigmentation and, consequently, the amount of light that reaches photoreceptors.6 Research also suggests that maintaining optimal serum levels of melatonin may be supportive for cranial comfort.‡7

While melatonin has a long history of use for sleep support, more recent research has indicated its umbrella of support has expanded to also include GI comfort, cranial comfort and ocular health. New research continues to emerge exploring the efficacy of melatonin in other areas, as well as synergistic actions with established treatment protocols.‡

References

  1. Zeitzer JM, Daniels JE, Duffy JF, et al. Do plasma melatonin concentrations decline with age? Am J Med 1999;107:432-436.
  2. Arendt J, Aldhous M, Marks V. Alleviation of jet lag by melatonin: preliminary results of controlled double blind trial. Br Med J 1986;292:1170-1171.
  3. Zhdanova IV, Wurtman RJ, Regan MM, et al. Melatonin treatment for age-related insomnia. J Clin Endocrinol Metab 2001;86:4727-4730.
  4. Field R. Melatonin may relieve sleep-cycle disorders. Med Tribune 1993(April 8):2.
  5. Lu WZ, Gwee KA, Moochhalla S, Ho KY. Melatonin improves bowel symptoms in female patients with irritable bowel syndrome: a double-blind placebo-controlled study. Aliment Pharmacol Ther 2005;22:927-934.
  6. Yi C, Pan X, Yan H, et al. Effects of melatonin in age-related macular degeneration. Ann N Y Acad Sci 2005;1057:384-392.
  7. Leone M, D’Amico D, Moschiano F, et al. Melatonin versus placebo in the prophylaxis of cluster headache: a double-blind pilot study with parallel groups. Cephalalgia 1996;16:494-496.