Catching ZZZs may retrieve lost memories

Fruit flies that snooze can overcome memory losses, raising hope for people with brain diseases that erase memories

Fruit flies, shown here, are used in many sleep experiments. New data show sleep can restore memory in even the most forgetful fruit flies.

Fruit flies, shown here, are used in many sleep experiments. New data show sleep can boost their ability to remember things. 

NASA/Dominic Hart

Sleep can restore memories in forgetful fruit flies, new data show. This raises hope that some extra ZZZs might also help people with Alzheimer’s disease and other memory disorders.

For a series of new experiments, researchers altered the genes of fruit flies. This caused various types of memory problems in the bugs. But the flies could get their memories back. All they needed was some solid snooze time.

“Quite honestly, this is a stunning result,” says Paul Shaw. A coauthor of the study, he works at Washington University in St. Louis, Mo. “We take flies that are bad and we make them better,” he notes. His team published details of its work online April 23 in Current Biology.

If the fly research can be translated to people, the results suggest that “we ought to take the frequent sleep disturbances in the aging population much more seriously,” says Maiken Nedergaard. She’s a brain researcher, or neuroscientist, at the University of Rochester Medical Center in New York. Even simple steps to promote sleep might benefit people with memory trouble, she says. Those steps can include getting more exercise and consuming less caffeine (which can make it hard to fall asleep).

Insects and people are different. That means the fly research doesn’t necessarily apply to us. Still, dozing fruit flies act a lot like people. Sleeping flies hold very still. Snoozing flies are hard to wake up.

The researchers used flies with gene changes, known as mutations. In one series of experiments, Shaw and his colleagues used different methods to get their flies to sleep more. One way was to drug the flies. The sleep that followed left these formerly befuddled flies sharper than ever. In a test of short-term memory, these flies better remembered to avoid an area treated with a nasty chemical (quinine).

And the well-rested flies retained a memory over several days. For instance, male flies learned not to waste time courting male flies that smelled like females. Two days after a failed courtship, the males remembered that rejection. They didn’t attempt to woo the males again.

The team got the flies to conk out in other ways, too. One was by turning on certain brain cells. Another involved increasing levels of a protein in the brain. Both methods also boosted memory. The results suggest that “It’s not how you make them sleep,” Shaw concludes. “It’s that they sleep.”

The scientits also studied flies that had a different mutation. This one affected a gene that in people is linked to certain forms of Alzheimer’s disease. That incurable disorder causes confusion, mood changes and problems with memory, language, behavior and solving problems. But sleep improved long-term memory in these flies as well.

The results build on other research on sleep and Alzheimer’s disease, notes  Mark Wu. A neurologist, he works at Johns Hopkins University in Baltimore, Md. Doctors have known for a long time that people with Alzheimer’s tend to sleep poorly. Research by Wu and others suggests that poor sleep might even worsen the disease. “We didn’t really appreciate until recently [that] possibility,” he says.

This research is still in its early stages, Wu cautions: So “it’s a stretch to suggest that sleeping would cure memory problems in Alzheimer’s disease patients.” But if sleep plays a role in Alzheimer’s disease, that’s important. Right now, he notes, there is no treatment for Alzheimer’s. But he notes that “sleep stuff we can treat.”

Power Words

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Alzheimer’s disease  An incurable brain disease that can cause confusion, mood changes and problems with memory, language, behavior and problem solving. No cause or cure is known.

caffeine  A stimulant, which activates the nervous system and heart. The leaves, seeds and fruits of many plants contain caffeine. In coffee plants and tea bushes, caffeine acts as a natural pesticide. It will kill or harm insects that attempt to dine on the plant. Caffeine is also toxic to some types of plants, bacteria — even frogs and dogs.

fruit flies  Tiny flies belonging to the species Drosophila melanogaster. Scientists often use these short-lived animals as a “guinea pig” for lab studies because they are easy to grow, can mature into adults in a short time and their bodies share many of the same traits and responses as more complex animals — including mammals.

gene   A segment of DNA that codes, or holds instructions, for producing a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

genetic  Having to do with chromosomes, DNA and the genes contained within DNA. The field of science dealing with these biological instructions is known as genetics. People who work in this field are geneticists.

long-term memory  The brain’s system for storing, maintaining and recalling information from the past.

mutation  Some change that occurs to a gene in an organism’s DNA. Some mutations occur naturally. Others can be triggered by outside factors, such as pollution, radiation, medicines or something in the diet. A gene with this change is referred to as a mutant.

neuroscience  Science that deals with the structure or function of the brain and other parts of the nervous system. Researchers in this field are known as neuroscientists.

proteins      Compounds made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. The hemoglobin in blood and the antibodies that attempt to fight infections are among the better known, stand-alone proteins.Medicines frequently work by latching onto proteins.

quinine  A bitter compound derived from the bark of the cinchona tree. Quinine has been used since the 1600s to treat malaria. It is also used as a flavoring agent in tonic water.

short-term memory  (also known as primary memory) The small amount of memory held actively in the mind for a short period of time, such as the series of digits in a telephone number.

shuteye  Slang for sleep

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