| The consensus appears to be that melatonin production declines with advancing age, although some studies failed to find an age-related decrease in healthy people. However, environmental and pathogenic factors influence melatonin levels, which may partly account for the discordance. For example, several drugs widely used by the elderly – including aspirin, ibuprofen, beta-adrenergic receptor antagonists and, ironically, benzodiazepines – appear to suppress melatonin production. Certain diseases common among middle aged and elderly patients potentially disturb sleep including depression, Parkinson’s disease and Alzheimer’s disease. In turn, sleep disturbances can influence melatonin production. Between 75% and 90% of people with insomnia are at increased risk of a co-morbid condition, such as gastro-oesophageal reflux, pain and neurodegenerative diseases. The elderly are also especially likely to present with insomnia due to restless legs syndrome, sleep apnoea and other primary sleep disorders. Furthermore, 40% of people with insomnia show concurrent psychiatric conditions, most commonly anxiety and depression, compared with 16% of controls. Anxiety and depression are both a cause and consequence of insomnia.
Overall, there is compelling evidence that melatonin levels are lower in middle-aged and elderly people that experience insomnia compared with subjects that report good sleep quality.
References
Lemoine et al, 2007 Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effects. J Sleep Res 2007-16:372/380
Zeitzer JM, Daniels JE, Duffy JF et al Do plasma melatonin concentrations decline with age? Am J Med 1999;107:432-6
Vissers FH, Knipschild PG, Crebolder HF Is melatonin helpful in stopping the long-term use of hypnotics? A discontinuation trial Pharm World Sci 2007;29:641-6
Barnard AR and Nolan PM When clocks go bad: neurobehavioural consequences of disrupted circadian timing PLoS Genet 2008;4:e1000040
Roth T Insomnia: definition, prevalence, etiology, and consequences J Clin Sleep Med 2007;3(5 Suppl):S7-10
Zeitzer JM, Duffy JF, Lockley SW, Dijk DJ, Czeisler CA Plasma melatonin rhythms in young and older humans during sleep, sleep deprivation, and wake Sleep 2007;30:1437-43
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