Melatonin cycle occurs later in older adults.




American Journal of Physiology Endocrinology and Metabolism

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Consumer Data: Insomnia, Sleep Disorders Melatonin
Professional Data: Insomnia, Sleep Disorders Melatonin


Good health and happiness are impossible when we are robbed of sleep for very long. For many people, this is all too often a way of life. One of mankind's oldest complaints, insomnia is the chronic inability to fall asleep or to stay asleep. While everyone occasionally experiences a sleepless night now and then without harm, long-term insomnia can be debilitating. After yet another night of inadequate sleep, insomnia sufferers typically report impaired mental and physical abilities, diminished memory, reduced alertness, and slow reaction times.

Melatonin is a brain hormone that regulates the body's sleep/wake cycles, also known as the "circadian rhythm." Available over-the-counter, melatonin has been become popular in recent years as a dietary supplement for promoting sleep. It has been suggested that changes in melatonin secretion may cause sleep disorders in people with certain nervous conditions. One group of psychiatric researchers has found that in many people mistakenly diagnosed with depression disruption of the circadian rhythm is the real problem.1 Melatonin does not occur in the diet, making supplementation the only source outside the body.

A recent investigation conducted in Boston, MA investigated the hormonal sleep cycles in older and younger Americans. The researchers examined the timing relationship between sleep and secretion of melatonin in regard to the circadian rhythm. The individuals involved did not experience any regular sleeping problems. The results showed that the secretion of melatonin was experienced earlier in the circadian rhythm in the older individuals rather than in the younger. Because of this early on activity, the elders slept and woke earlier. The melatonin levels were higher in the elders when they woke up compared to the relatively low levels in those who were younger. These results illustrated a change in the sleep/wake cycle and sleep timing associated with aging. The authors concluded, "In healthy older subjects, the relative timing of the melatonin rhythm with respect to sleep may not play a causal role in sleep disruption."2


1. Kayumov L, et al. Melatonin, sleep, and circadian rhythm disorders. Semin Clin Neuropsychiatry. Jan2000;5(1):44-55.
2. Duffy J. Peak of circadian melatonin rhythm occurs later within the sleep of older subjects. American Journal of Physiology--Endocrinology and Metabolism. Feb 2002;282:E297-E303.