A team of scientists in Japan has found a promising new way to support memory and brain health as we grow older—by using something that comes from a common sleep hormone. The research, led by Tokyo Medical and Dental University, focused on melatonin, a natural chemical in the body best known for helping us sleep.
But the study discovered that melatonin might also play a surprising role in protecting memory—thanks to the substances it breaks down into after being processed in the body.
When melatonin is absorbed, it doesn’t just help you fall asleep. It also turns into several other substances, known as metabolites. The researchers looked closely at one of these metabolites, called AMK. They wanted to see if it could help prevent or slow down memory loss, which is something many people experience with age.
To test this idea, the scientists used mice, since these animals are often studied in memory research. Mice have a natural habit: when given a choice between a new object and one they’ve already seen, they’ll usually spend more time exploring the new one.
This shows that they remember the old object. But if a mouse has memory problems, it will treat both objects the same, as if it doesn’t remember either one.
In the study, the researchers showed the mice several objects to get them familiar. Then they gave the mice melatonin or its different breakdown products, including AMK. The next day, they tested the mice again to see which objects they recognized.
The results were exciting: the mice that received the melatonin metabolites had much better memory, especially those given AMK. They were more likely to recognize the familiar objects and spent more time exploring the new ones.
The scientists then looked at what was happening inside the mice’s brains. They found that AMK and the other melatonin by-products had built up in the hippocampus, the brain’s memory center. This part of the brain is critical for forming long-term memories.
When the researchers blocked melatonin from turning into AMK, the memory-boosting effect disappeared—suggesting AMK plays a central role in helping the brain remember.
One of the most hopeful parts of the study was that the benefits of AMK were seen in all the mice, not just the young ones. Even older mice—who normally show signs of memory loss—improved after being given AMK. That’s important, because memory problems are much more common as we age.
In humans, memory decline in older age can sometimes lead to conditions like Mild Cognitive Impairment (MCI), which in some cases develops into Alzheimer’s disease.
While this study was done in animals, the findings are exciting because they suggest that one day, melatonin’s metabolites—especially AMK—might be used to help people keep their memory strong as they get older. If similar effects are confirmed in humans through future research, this could lead to new ways of slowing down or even preventing cognitive decline.
The study was published in the Journal of Pineal Research, a scientific journal that focuses on studies involving melatonin and related topics. Although more work needs to be done, this discovery brings hope that a well-known sleep hormone and its natural by-products might also help protect our brains and memories as we age.
If you care about brain health, please read studies about how the Mediterranean diet could protect your brain health, and Omega-3 fats and carotenoid supplements could improve memory.
For more information about brain health, please see recent studies about antioxidants that could help reduce dementia risk, and higher magnesium intake could help benefit brain health.
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