UH Researchers Say Sleep Hormone May Disrupt Night Memories

A new study by a team of University of Houston researchers suggests a hormone that helps regulate sleep cycles in humans could actually hurt memory formation at night. As Houston Public Radio's Jack Williams reports, the so-called "hormone of darkness", melatonin appears to disrupt nighttime memories in zebrafish.

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The research was published earlier this month in Science, a leading research journal and suggests melatonin could actually hurt memories that are formed at night, while possibly allowing the consolidation of older memories.

"I was really surprised that this difference in learning was in fact due to the presence and absence of melatonin so we tested that and it was surprising. I was surprised."

University of Houston assistant professor of biology and biochemistry Gregg Roman and his team of researchers used zebrafish, which are diurnal and react to the daylight cycle in a similar fashion to humans, to test their reaction to melatonin. He says the loss of nighttime memories and the ability to learn at night could be sacrificed for a purpose.

"What I think is happening, this is just a hypothesis, but what I think is happening is that melatonin in quieting the learning circuit so that consolidation of previous memories can occur. In other words, if these neurons and these neurocircuits that are involved in memory were not shut down then you can confuse the previous memories with maybe new memories that you're trying to form."ξξξ

Melatonin as a supplement is a popular sleep aid and powerful antioxidant. Roman says there's a possibility that blocking melatonin signals for some people might actually help them stay awake and learn better at night.

"If melatonin has the same response in people then people who have night shifts, people who have to learn things at night might in fact be inhibited from learning those and they might be able to improve their performance by either using very, very bright lights to inhibit melatonin or to use certain drugs that will inhibit melatonin signaling and that way they can better form memories."

Roman says despite his research, melatonin is not the enemy.

"I think probably melatonin is a very positive thing for all of us except if we are trying to cram late at night for that exam the next day."ξ

You can see the melatonin report in Science through a link on our website, KUHF.org.


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