It's Not About Global Warming This Time, But It Is Another Case Of Scientific Non-Consensus
There's competing and compelling evidence that healthy older people do not need to take supplemental melatonin after all
An earlier post provided a couple of research study graphs indicating nighttime peak values of plasma melatonin in people on the far side of 30 or 40 dropped well below the high values characteristic of younger people, suggesting melatonin supplementation might be a healthy tactic to follow in a person’s older years. A slightly later study by Zeitzer et al. (1999) challenges these data in the cases of older people in good health, however:
Our results do not support the contention that nocturnal plasma melatonin concentrations decrease with healthy aging. Rather, the endogenous circadian melatonin rhythm in most healthy, drug-free older people has an amplitude comparable to that of young adults. There may be a small group of older adults who have significantly lower melatonin amplitude, as has been observed in one previous study. Our findings challenge the conventional belief that plasma melatonin concentrations decline systematically with advancing age because of an increase in pineal calcification or other biochemical change. This decline has been thought to act as an “aging clock”, a hypothesis that our data do not support.
These results do not support the hypothesis that reduction of plasma melatonin concentration is a general characteristic of healthy aging. Should melatonin replacement therapy or melatonin supplementation prove to be clinically useful, we recommend that an assessment of endogenous melatonin be carried out before such treatment is used in older patients.
The competing graph data:
Some formal academic crossing of swords followed the above sally:
https://www.amjmed.com/article/S0002-9343(00)00515-5/fulltext#relatedArticles, then
https://www.amjmed.com/article/S0002-9343(00)00518-0/fulltext
It seems to me that the Zeitzer et al. (1999) won the contest on points, and that the second paragraph of the quote from the paper provided here remains good advice.