I don't have access to the actual study but I wonder if they had access to any metrics for the individuals that could quantify the intensity of the insomnia. Chronic insomnia/sleep deprivation is already correlated with heart disease. Could it be that the people with worse insomnia were more likely to take melatonin but also more likely to have heart issues due to the insomnia alone?

> “Worse insomnia, depression/anxiety or the use of other sleep-enhancing medicines might be linked to both melatonin use and heart risk,” Nnadi said. “Also, while the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship. This means more research is needed to test melatonin’s safety for the heart.”

This seems pretty critical, no? I would assume that melatonin use increases with the severity of insomnia, and persistent lack of sleep has a whole host of long-term health implications. So insomnia a priori seems highly likely to cause both increased melatonin consumption and heart disease. Given how obviously confounded this causal system is, it's practically negligent to not at least control for severity of insomnia or something. Ideally they should have done a matched study or DID or something, but without any attempt to account for the confounding this study is just clickbait.

Okay but how are people using it? It can so easily be misused: it's a signalling hormone that resets the phase alignment of the circadian rhythm. Yet so many people just eat it randomly like a sleeping pill. That's bound to be damaging in the long term. It shouldn't be necessary to take it every single night. If you're having trouble sleeping every single night, you've got other issues. Maybe you're stressed out by the world you live in. Maybe it means you're taxing your central nervous system, throttling it constantly. You need to go around the glutamate–glutamine cycle more often than you can sustain. There are metabolic costs to doing this. Maybe you've been eating food from soil devoid of minerals like magnesium, a critical cofactor in the glutamate-glutamine cycle. In fact people struggling with chronic stress have been shown to be statistically more likely to be insufficient or deficient in magnesium.

But you take melatonin because nobody wants to tell you all this. And you take it at random times thereby fucking up your circadian rhythm even worse.

Don't get me started on vitamin D and how that's _also_ a circadian phase signaller, but how I never see those big flashy press releases about whether or not vitamin D is good or bad ever go into this.

Why do I have so little faith that they controlled for timing in the study?

Interesting and importantly both groups were those who had insomnia and those who had previously been diagnosed with heart failure were excluded.

"People who are concerned enough about their insomnia to get a prescription from their doctor and take it regularly are more likely than other people to have heart problems and other health issues"

Good to know but maybe not particularly compelling?

melatonin is an awsome dream drug great for a midwinter cleanup of the unconsious attic but looses its zap, quickly