Role of Melatonin Supplementation in Neurodegenerative Disorders


Melatonin is a hormone secreted by the pineal gland in the human brain. It helps regulate other hormones and maintains the body’s circadian rhythm, which plays a critical role in when the body falls asleep and wakes up. When exposed to dark, the human body produces more melatonin. Likewise, the production of melatonin drops when the human body is exposed to light. Exposure to bright lights in the evening, or too little light exposure during the day, can disrupt the body’s normal melatonin cycles.1


Lower levels of melatonin have been observed in both the blood and in cerebrospinal fluid (the fluid that surrounds the brain and spinal cord) from Alzheimer’s disease patients. Researchers have observed that the concentration of melatonin in cerebrospinal fluid decreases with the progression of Alzheimer’s disease. Also, the melatonin levels in cerebrospinal fluid and in the human pineal gland are already reduced in Alzheimer’s disease patients who exhibit the earliest signs of Alzheimer’s disease neuropathology prior to detectable cognitive impairment. Measurement of melatonin concentration in their cerebrospinal fluid has therefore been proposed as a potential early marker for the detection of Alzheimer’s disease.

The antioxidant and anti-inflammatory properties of melatonin may play a neuroprotective role in neurodegenerative disorders. Researchers have found that melatonin supplementation in patients with Alzheimer’s disease significantly slows down the progression of their cognitive impairment, improves their sleep, and decreases their brain atrophy.


This review article, published in Frontiers in Bioscience, was written to evaluate the literature on the protective effects of melatonin on Alzheimer’s disease, Parkinson disease, Huntington’s disease and Amyotrophic Lateral Sclerosis.2

In the human body, reactive oxygen species are formed as a natural byproduct of the normal metabolism of oxygen and have important roles in cell signaling and homeostasis. However, reactive oxygen species levels can increase dramatically during times of environmental stress, which may result in significant damage to cell structures (oxidative stress). These excessive reactive oxygen species are involved in the neuronal death associated with Alzheimer’s disease. Melatonin is a free radical scavenger, meaning it can help deal with excessive reactive oxygen species. This has led researchers to investigate the effects of antioxidants, including melatonin, in preventing or delaying the events leading to neuronal destruction.

Several of the studies the researchers reviewed were limited by small sample sizes, and they noted that additional studies are required to test the clinical efficacy of melatonin supplementation and to identify the specific therapeutic concentrations needed.

  1. University of Maryland Medical Center. Melatonin. Accessed September 6, 2016.
  2. Polimeni G, Esposito E, Bevelacqua V, Guarberi C, Cuzzocrea S. Role of melatonin supplementation in neurodegenerative disorders Frontiers in Bioscience (Landmark Ed). 2014. 1;19:429-46.






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