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Cognitive Health


According to a study that included 88,094 individuals, there is an association between irregular sleep patterns and the risk of dementia. Sleep regularity was defined as how consistent individuals were in going to bed and waking at the same time. The researchers found that people with the most irregular sleep patterns were 53% more likely to develop dementia compared to those who had regular sleep patterns (1).

Overall, clinical data suggest that melatonin supplementation improves sleep and neurotransmission and reduces sundowning in those with Alzheimer’s disease. At a mechanistic level, it may decrease the progression of the disease through its protection of neuronal cells from amyloid-beta, possibly due to the facilitation of its degradation and transport from the brain matter through the glymphatic fluid (2-4). In a small pilot study of elderly patients with a mild cognitive deficit, the ability to remember previously learned items improved, and depression decreased with melatonin (5). A more extensive, longer-term study found that patients with mild cognitive impairment scored better on the Mini-Mental Status Exam and the Sleep Disorders Index when taking melatonin (6). Oxidative stress is one of the leading causes of age-related brain dysfunction by impairing neurogenesis. Thus, researchers are exploring influences on monoamine synthesis, a common target for diseases of the aging brain (7,8), as well as the potential of melatonin as a therapeutic in dementia.


Authors: Deanna Minich, Ph.D., Melanie Henning, ND, Catherine Darley, ND, Mona Fahoum, ND, Corey B. Schuler, DC, James Frame

Reviewer: Peer-review in Nutrients Journal

Last updated: December 18, 2023



1. Yiallourou SR, Cribb L, Cavuoto MG, Rowsthorn E, Nicolazzo J, Gibson M, et al. Association of the Sleep Regularity Index With Incident Dementia and Brain Volume. Neurology. 2024 Jan 23;102(2).

2. Lin L, Huang QX, Yang SS, Chu J, Wang JZ, Tian Q. Melatonin in Alzheimer’s disease. Vol. 14, International Journal of Molecular Sciences. 2013. p. 14575–93.

3. Roy J, Tsui KC, Ng J, Fung ML, Lim LW. Regulation of melatonin and neurotransmission in Alzheimer’s disease. Vol. 22, International Journal of Molecular Sciences. 2021.

4. Li Y, Zhang J, Wan J, Liu A, Sun J. Melatonin regulates Aβ production/clearance balance and Aβ neurotoxicity: A potential therapeutic molecule for Alzheimer’s disease. Vol. 132, Biomedicine and Pharmacotherapy. 2020.

5. Jean-Louis G, von Gizycki H, Zizi F. Melatonin effects on sleep, mood, and cognition in elderly with mild cognitive impairment. J Pineal Res. 1998;25(3).

6.Furio AM, Brusco LI, Cardinali DP. Possible therapeutic value of melatonin in mild cognitive impairment: A retrospective study. J Pineal Res. 2007;43(4).

7. Tractenberg RE, Singer CM, Cummings JL, Thal LJ. The Sleep Disorders Inventory: An instrument for studies of sleep disturbance in persons with Alzheimer’s disease. J Sleep Res. 2003;12(4).

8. Esteban S, Garau C, Aparicio S, Moranta D, Barceló P, Fiol MA, et al. Chronic melatonin treatment and its precursor L-tryptophan improve the monoaminergic neurotransmission and related behavior in the aged rat brain. J Pineal Res. 2010;48(2).

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