Memory could depend on the time of day, study in mice suggests © Getty Images

Memory could depend on the time of day, study in mice suggests

The researchers believe that the genes controlling the circadian rhythm also affects memory and learning.

Finding something difficult to remember? Try waiting until later in the day. Researchers at the University of Tokyo have identified a gene in mice that seems to influence the ability to recall memories at different times of day.

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To make the discovery, the team observed young adult mice as they explored a new object for a few minutes. They then removed it for a set period and then reintroduced it. As mice spend less time touching an object they remember seeing, the team were able to determine the degree to which they remembered the object.

They found that mice were more likely to recognise the object if they saw it for the first time just before they normally woke up and saw it again just after they normally went to sleep. Mice that saw the object just before they normally woke up both times, 24 hours apart, did not recognise it.

They then repeated the experiments with mice without BMAL1, a protein linked to circadian rhythms that is naturally found in lower levels just after waking. These mice were even more forgetful just before they woke up. This suggests that the circadian clock that is responsible for regulating sleep-wake cycles also affects learning and memory formation.

“We may have identified the first gene in mice specific to memory retrieval,” said Professor Satoshi Kida from the University of Tokyo. “Now we have evidence that the circadian clocks are regulating memory recall. If we can identify ways to boost memory retrieval through this BMAL1 pathway, then we can think about applications to human diseases of memory deficit, like dementia and Alzheimer’s disease.”

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