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Alzheimer's Disease and Melatonin

Melatonin is a natural hormone that regulates sleep. At night, the pineal gland stops producing serotonin and instead makes melatonin. This melatonin release helps trigger sleep. Studies have shown that melatonin, along with light therapy (exposure to bright light during daylight hours) may help Alzheimer's patients with quality of sleep and mood.

Effect of Melatonin on Alzheimer's Disease

The combination of melatonin and light therapy (bright light exposure during daylight hours) has shown to improve both mood and quality of sleep, which can be significant part of Alzheimer's symptoms.

Read more details about Melatonin.

Research Evidence on Melatonin

In a sizable Danish trial, researchers investigated the effects of melatonin and light therapy (bright light exposure during daylight hours) on mood, sleep, and cognitive decline in elderly patients, most of whom suffered from dementia.85 They found that melatonin 2.5 mg, given nightly for an average of 15 months, slightly improved quality of sleep, but it worsened mood. Melatonin apparently had no significant effect on cognition. On the other hand, light therapy alone slightly decreased cognitive and functional decline and improved mood. Combining melatonin with light therapy improved mood and quality of sleep.

Safety Issues

A safety study found that melatonin at a dose of 10 mg daily produced no toxic effects when given to 40 healthy males for a period of 28 days. 1 However, this does not prove that melatonin is safe when taken on a regular basis over the long term. Keep in mind that melatonin is not truly a food supplement but a hormone. As we know from other hormones used in medicine, such as estrogen and cortisone, harmful effects can take years to appear. Hormones are powerful substances that have many subtle effects in the body, and we're far from understanding them fully. While in one small study, use of melatonin over an 8-day period by healthy men did not affect natural release of melatonin or levels of pituitary or sex hormones, 2 another study found effects on testosterone and estrogen metabolism in men and possible impairment of sperm function. 3 Also, a small study in women found possible effects on the important female hormone called LH (luteinizing hormone). 4 Melatonin appears to cause drowsiness and decreased mental attention for about 2 to 6 hours after using it and may also impair balance. 5 For this reason, you should not drive or operate machinery for several hours after taking melatonin. In a study of healthy middle-aged and older adults, however, an extended release version of melatonin, which is said to more closely mimic natural fluctuations of the hormone in the body, did not impair mental ability or driving skills 1 to 4 hours later compared to placebo. 6 In either case, melatonin does not appear to have any "hangover" effects the following day. 7 Based on theoretical ideas of how melatonin works, some authorities specifically recommend against using it in people with depression, schizophrenia, autoimmune diseases, and other serious illnesses. One study in postmenopausal women found evidence that melatonin might impair insulin action and glucose tolerance, suggesting that people with diabetes should not use it. 8 However, another study found melatonin safe and effective for people with diabetes. 9 Because of these contradictions, we suggest that individuals with diabetes seek physician supervision before using melatonin.

Two exceedingly preliminary studies reported by one research group has led to publicized concerns that use of the supplement melatonin might increase night-time asthma. 10 However, one double-blind study of melatonin in people with asthma found evidence of improved sleep without worsening of symptoms. 11 Again, at the current state of knowledge, caution must be advised for people with night-time asthma who wish to try melatonin.

There is some evidence that melatonin may interfere with the ability of blood to clot normally, at least in healthy volunteers, 12 though the clinical significance of this finding is at yet unknown.

Maximum safe dosages for young children, pregnant or nursing women, or those with serious liver or kidney disease have not been established.


  1. de Lourdes M, Seabra V, Bignotto M, et al. Randomized, double-blind clinical trial, controlled with placebo, of the toxicology of chronic melatonin treatment. J Pineal Res. 2000;29:193-200.
  2. Rajaratnam SM, Dijk DJ, Middleton B, et al. Melatonin phase-shifts human circadian rhythms with no evidence of changes in the duration of endogenous melatonin secretion or the 24-hour production of reproductive hormones. J Clin Endocrinol Metab. 2003;88:430-39.
  3. Luboshitzky R, Shen-Orr Z, Nave R, Lavi S, Lavie P. Melatonin administration alters semen quality in healthy men. J Androl. 23(4):572-8.
  4. Kripke DF M D, Kline LE D O, Shadan FF M D Ph D, et al. Melatonin effects on luteinizing hormone in postmenopausal women: A pilot clinical trial NCT00288262. BMC Womens Health. 2006 May 16 [Epub ahead of print].
  5. Graw P, Werth E, Kräuchi K, Gutzwiller F, Cajochen C, Wirz-Justice A. Early morning melatonin administration impairs psychomotor vigilance. Behav Brain Res. 121(1-2):167-72.
  6. Otmani S, Demazières A, Staner C, Jacob N, Nir T, Zisapel N, Staner L. Effects of prolonged-release melatonin, zolpidem, and their combination on psychomotor functions, memory recall, and driving skills in healthy middle aged and elderly volunteers. Hum Psychopharmacol. 23(8):693-705.
  7. Paul MA, Brown G, Buguet A, Gray G, Pigeau RA, Weinberg H, Radomski M. Melatonin and zopiclone as pharmacologic aids to facilitate crew rest. Aviat Space Environ Med. 72(11):974-84.
  8. Cagnacci A, Arangino S, Renzi A, et al. Influence of melatonin administration on glucose tolerance and insulin sensitivity of postmenopausal women. Clin Endocrinol (Oxford). 2001;54:339-346.
  9. Garfinkel D, Wainstein J, Halabe A, et al. Beneficial effect of controlled release melatonin on sleep quality and hemoglobin A1C in type 2 diabetic patients. Presented at: World Congress of Gerontology; July 1-6, 2001; Vancouver, Canada.
  10. Sutherland ER, Ellison MC, Kraft M, Martin RJ. Elevated serum melatonin is associated with the nocturnal worsening of asthma. J Allergy Clin Immunol. 112(3):513-7.
  11. Campos FL, da Silva-Júnior FP, de Bruin VM, de Bruin PF. Melatonin improves sleep in asthma: a randomized, double-blind, placebo-controlled study. Am J Respir Crit Care Med. 170(9):947-51.
  12. Wirtz PH, Spillmann M, Bärtschi C, Ehlert U, von Känel R. Oral melatonin reduces blood coagulation activity: a placebo-controlled study in healthy young men. J Pineal Res. 44(2):127-33.

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1 Comment

Posted 12 years ago

Origins In Cells Clusters, Intercell Cleanup

I Antidepressants show signs of countering Alzheimer’s Human brain scans and mice data link serotonin-boosting drugs with reduced plaque density.

II Interesting. So what else is new? posted by Dov Henis on 15 Mar 2009 at 9:50 pm origin written 2005 Life Is Simpler Than They Tell Us Evolution: Genes to Genomes to Monocellular to Multicellular Organisms; Direct Sunlight to Metabolic Energy, Too; Tryptophan to Serotonin to Melatonin to Neural System. (cue for intercell cleanup time)

A. Tryptophan to Serotonin to Melatonin

Melatonin is a hormone secreted by the human pineal gland during night-time darkness. It is now marketed in the US as a nutritional supplement. The hormone is an indolamine compound derived from the essential amino acid L-tryptophan, with serotonin as an intermediate precursor.

Tryptophan is one of eight essential amino acids, not produced by the body but coming from the diet. The additional fourteen amino acids are produced metabolically.

In the brain, tryptophan converts to serotonin, the neuro-transmitter. Tryptophan is the only source for serotonin in the brain. Insufficient L-tryptophan in the diet is a cause of many severe biological malfunctions.

Some serotonin is converted in the pineal gland to melatonin, the hormone involved in intercell processes during sleep time.

B. Sunlight to Metabolic Energy

Bio-clocks are products of the innate sun-dictated active-inactive pattern of genes and genomes, parents of Earth's life. During life genesis and its early evolution direct sunlight was the only source of their usable energy. This situation persisted well into the evolution of the early monocellular organisms, and both genes and genomes display, therefore, innate "inactive-sleep" phenomena.

The incorporation of mitochondria with some cells initiated the metabolic bio production of bio usable energy and furnished the evolving monocellular organisms with new, additional, flexibly available local energy. This development opened up a variety of courses of evolutions of cultures of monocells communities.

C. Individual Monocells to Cooperative Monocells-Communities

As individual independent genes aggregated to cooperative genes communes, genomes, so individual monocells aggregated cooperatively into monocellular communities, cultures. "Life has always been and still is a fractal affair, repetition of phenomena on ever more complex scale. It cannot be otherwise; it evolves. And surviving-proliferating life has always been a cooperative affair since cooperation is most successful for overall survival/proliferation."

Cooperation requires all sorts of interactions, including maintenance, protection and foraging for food-energy. Organisms' interactions are "cultures". Cultures require "cultural energy". Melatonin and some proteins are dark-and-light cue signals evolved by the monocells communities for timing intercells processes when the intracells processes are at "sleep-inactive" state. Melatonin is a derivative of serotonin a derivative of tryptophan, and proteins are genes' tools, energy-dependent metabolism products.

D. Monocellular to Multicellular Organisms, Monocells Culture to Neural System

Now we can appreciate the fractal nature of life's evolution. It is ever-continuous ever-enhanced ever-complexing cooperation. Now we can understand why, and grosso modo how, all the organs and processes and signals found in multicelled organisms have their origins in the monocells communities. And this includes the functions of serotonin and melatonin and, yes, the evolution of neural cells and the neural systems with their intricate outer-membrane shapes and functions and with their high energy consumption requirements.

Now, circa four billion years after initial genesis-evolution with direct sun's energy followed with evolution with also indirect, bio, sun's energy, some of Earth life, we humans, find ourselves short of energy and in need of exploiting again more, and more directly, our sun's energy...

Dov Henis (comments from 22nd century)

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