Good news teenagers: a little extra sleep might have more benefits than previously thought. New research with fruit flies shows that a few extra hours of shut eye might hold the key to restoring the memory lost to neurodegenerative diseases.
Fruit flies have traditionally been used for scientific studies because they have a well mapped genome (DNA) with a lot of similarities to human genes. This genetic similarity and the fact that fruit flies are easy to mutate and relatively inexpensive allow scientists to use fruit flies to draw conclusions about potential change in humans as well. Researchers at Washington University School of Medicine studied the effects of increased sleep on short and long term memory in mutant fruit flies that have trouble making memories. Results showed that increased sleep, equal to about three to four hours over two nights for humans, restored memory in the mutant fruit flies.
Researchers tested three types of mutant fruit flies that had gene defects in either the rut gene, dnc gene (impair formation of memory), or the presenilin gene, which has been linked to early onset Alzheimer’s disease in humans. The researchers induced sleep using three different methods: by using a drug, increasing dFabp expression (a protein involved in sleep), or activating the neurons in the fan-shaped body region of the fruit fly brain. Researchers tested changes in memory by comparing the flies that got extra sleep to their sibling flies who did not receive one of the three treatments above.
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To test long-term memory, the researchers used something called courtship conditioning, and to test for short-term memory, the researchers used aversive phototaxic suppression (APS). APS tests a flies’ ability to learn to avoid light that is paired with some negative stimulus, like humidity or quinine (bitter taste).
Results showed that extra sleep restored brain functions in fruit flies with mutated memory genes, and that the method used to induce sleep did not change this fact. More simply, sleep allowed the flies to regain brain function that was removed by mutation. In the Alzheimer’s disease model fly, sleep was shown to reverse defects in long-term memory.
In conclusion, the researchers suggest that their findings show that the brain, when asleep, has a large capacity for behavioral change that is not possible when awake. While more research needs to be done to understand the mechanisms behind these findings, this adds to a growing body of research that suggest that sleep may hold the key to treating memory loss.
Feature Image Source: Now why am I here ? by Neil Moralee
