Scientists at Washington University School of Medicine in St. Louis have created a new line of fruit flies that they think have the potential to pinpoint the causes of insomnia in humans.
According to researchers, the study of insomniac fruit flies could also help develop ways to test or treat the sleeping disorder in humans.
"Insomnia is a common and debilitating disorder that results in substantial impairments in a person's quality of life, reduces productivity and increases the risk for psychiatric illness," says senior author Paul Shaw, Ph.D.
"We think this model has clear potential to help us learn more about the causes of insomnia and someday develop ways to test for or treat them in the clinic," he added.
As he studied the healthy flies, Shaw noticed that a few flies naturally slept less than others. He decided to take flies with insomnia-like characteristics and breed them to amplify those qualities.
The flies he bred had difficulty falling asleep in normal circumstances, and their sleep was often interrupted or fragmented. He also used hyper-responsiveness to stimuli as a breeding guide.
For example, if researchers turned on a light at night, insomniac flies woke and stayed up the rest of the night, while the healthy flies went back to sleep. The flies that stayed up were added to the breeding pool.
After generations of selective breeding, the researchers produced a line of flies that naturally spent only an hour a day asleep-less than 10 percent of the 12 hours of sleep normal flies get.
They noticed an obvious and surprising behavioral change: even though flies have six legs, the insomniac flies fell over more often.
"We sent them to experts in neurodegeneration in flies to see if their lack of sleep or the breeding had somehow damaged their brains. But the experts said there weren't any physical brain abnormalities," Shaw said.
When researchers screened the genome of the insomniac flies for changes in gene activity levels, they found altered activity levels for genes involved in metabolism, nerve cell activity and sensory perception.
The findings are published June 3 in The Journal of Neuroscience.