Melatonin is best known as the natural hormone that helps control our sleep and wake cycle. The brain releases more melatonin at night, telling the body that it is time to rest.
Many people also take melatonin supplements to help with jet lag or sleep problems.
Now, scientists have found that this hormone may have another important job—helping to keep our memory healthy as we get older.
A research team from Tokyo Medical and Dental University studied how melatonin affects the brain.
Their findings, published in the Journal of Pineal Research, suggest that melatonin and one of the substances it turns into inside the body could improve memory and may one day help protect against age-related memory loss and diseases such as Alzheimer’s disease.
After melatonin is produced, the body breaks it down into smaller compounds called metabolites.
The researchers wanted to know whether these metabolites might actually be responsible for many of melatonin’s effects on the brain. Earlier studies had suggested that melatonin could support brain health, but the exact reason was still unclear.
To investigate, the scientists carried out experiments in mice using a well-known memory test. Mice are naturally curious and spend more time looking at objects they have never seen before. If they remember an object from an earlier visit, they quickly lose interest in it. Mice with poor memory, however, treat familiar objects as if they are completely new.
In the study, the mice first explored several objects. One hour later, they received either melatonin or one of its two main metabolites. The researchers tested their memory the following day by seeing whether the mice could recognize the familiar objects.
The results were encouraging. Mice that received melatonin or its metabolites remembered the objects better than untreated mice. One metabolite, called AMK, produced the strongest improvement in memory, making it the most promising compound in the study.
The team also examined the animals’ brains. They found that melatonin and its metabolites collected in the hippocampus, a part of the brain that plays a key role in forming and storing memories. When the researchers blocked the body’s ability to convert melatonin into AMK, the memory benefits disappeared. This showed that AMK was essential for the memory-boosting effect.
Another important finding was that AMK improved memory in both young and older mice. This is especially significant because memory naturally becomes weaker with age. If future studies find similar results in people, AMK could become a possible treatment for age-related memory decline or mild cognitive impairment, often called MCI.
Mild cognitive impairment causes noticeable problems with memory and thinking that are greater than normal aging but not severe enough to interfere greatly with daily life. Some people with MCI later develop Alzheimer’s disease, while others remain stable or even improve. Finding safe ways to protect memory at this early stage is an important goal for researchers.
Although these findings are promising, the study was carried out only in mice, so more research is needed before the treatment can be tested in people.
Even so, the work led by Dr. Atsuhiko Hattori offers fresh hope that natural substances related to melatonin may one day help preserve memory, keep the brain healthier for longer, and reduce the impact of age-related memory loss.
If you care about brain health, please read studies about Vitamin B9 deficiency linked to higher dementia risk, and flavonoid-rich foods could help prevent dementia.
For more health information, please see recent studies that cranberries could help boost memory, and how alcohol, coffee and tea intake influence cognitive decline.
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