Melatonin effect of sleeplessness in elderly.

 

Introduction

 Sleeplessness or in a broader view insomnia is great problem among elderly related people around the globe. Elderly people are more prone to social isolation due to several social factors behind the scenario. Increase of morbidity, health issues, disturbed physiological functions, mental irresponsiveness are some of the factors that are seen more prone in elderly individuals. However some of the medical conditions like dementia, schizophrenia, depression, chronic obstructive pulmonary disease, congestive heart failure and concomitant medicines are also relevant factors for insomnia among the elderly. Several medicines like serotonin re-uptake inhibitors, dopamine agonists, antipsychotic drugs, and theophylline, anti- convulsants, decongestants, beta –agonist, anti hypertensive drugs, caffeine, thyroid hormone, diuretics and alcohol are also responsible factors for the cause of insomnia among elderly subjects.

Physiology of Melatonin Synthesis

“In human being the plasma level of melatonin is high during sleep. The length and darkness period decide the duration and magnitude of the hormone secretion by the pineal gland so that the hormone acts as a micro-endocrine mediator of the photo period. Presence of light has been seen as the suppressor of the melatonin hormone secretion. A type of nucleus is present in the hypothalamus known as suprachaismatic nucleus and it is known as the pacemaker for maintaining the circadian rhythm. In the retina the photoperiod information are conveyed and reach the suprachaismatic nucleus and these periods than reach the pineal gland through a pathway known as synaptic pathways innervating from the cervical ganglia. The nor-epinephrine from the sympathetic nerves is responsible for the control of melatonin synthesis. The dietary amino acids tryptophan from the circulation to pineal gland is the first step in the synthesis of melatonin. Tryptophan is then converted to 5-hydroxytryptophan by the enzyme tryptophan hydroxylase and then to 5- hydroxytryptamine (serotonin) by the enzyme 5-hydroxytryptophan decarboxylase. Subsequently, serotonin is acetylated by araylalkylamine N-acetyl transferase (AA-NAT) to N-acetyl serotonin (NAS), which is the rest limiting step in melatonin bio-synthesis. Finally NAS is O-methylated to melatonin by hydroxyindole –O-methyl transferase”1.

Factors responsible for the depletion of Melatonin level in aging

1.     1. “Metabolism of melatonin occurs in the liver and urinary excretion of melatonin occurs as 6-sulphatoxymelatonin, therefore urinary excretion of 6-sulphatoxymelatonin serves as reliable profile for the measurement of serum melatonin level. It is seen that urinary excretion of 6 SMT is less in urine in elderly individuals and this may contribute as a relevant factor for the frequency of sleep disorders in elderly individuals”2.

    2. “Suprachiasmatic nucleus is regarded as the pacemaker for the maintenance of sleep rhythm and is located in the Hypothalamus. Any abnormality in the suprachiasmatic nucleus leads to poor sleep”3.

3.     3.  Medical conditions like Alzimers disease, Schizophrenia, Depression, Chronic Obstructive Pulmonary Disease, Congestive Heart Failure, and Dementia are some of the relevant factors that lead to poor sleep and these medical conditions are responsible for the depletion of Melatonin level in elderly individuals.

4.    4.   Certain medicines may favor or cause insomnia in elderly individuals. Serotonin reuptake inhibitors, dopamine agonists, anti-psychotics, theophylline, anti-convulsants, decongestants, beta agonists, anti hypertensive drugs, caffeine, thyroid hormone, diuretics, alcohol and niacin are some of the examples responsible for the depletion of melatonin level in elderly individuals4.

Reference:-

1.      1. Physiology and metabolic functions of melatonin by J. Barrenetxe, P. Delagrange and J.A Martinez, https://pubmed.ncbi.nlm.nih.gov/15352385/.

2.    2.  Improvement of sleep quality in elderly people by controlled release melatonin, D Garfinkel, M laudon, D Nof, N Zisapel, https://pubmed.ncbi.nlm.nih.gov/7658780/.

3.     3. The effectiveness of melatonin for insomnia in older adults: A systemic review by John..J. Harrington, https://core.ac.uk/download/pdf/210607224.pdf.

4.   4.   Physiology and metabolic functions of melatonin by J. Barrenetxe, P. Delagrange and J.A Martinez, https://pubmed.ncbi.nlm.nih.gov/15352385/.



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