Starvation and sleep-deprivation may keep brain sharp

Stay hungry and sleep-deprived to stay sharpu00a0-- that seems to be the idea, at least as far as fruit flies are concerned.

New research from Washington University in St. Louis suggests that, in fruit flies, being hungry may provide a way to stay awake without feeling groggy or mentally challenged.

The study showed that starvation nearly tripled the amount of time they could survive without sleep. This happens because of a protein that helps the fruit fly brain manage its storage and use of lipids, a class of molecules that includes fats such as cholesterol and fat-soluble vitamins such as vitamins A and D.

Clay Semenkovich said the results fit into a growing awareness that organisms use lipids for much more than energy storage.

"If you identify the appropriate lipids involved in sleep regulation and figure out how to control them, you may be able to decrease suffering associated with loss of sleep or the need to stay awake," he said.

Like humans, flies deprived of sleep one day will try to make up for it by sleeping more the next day, a phenomenon referred to as sleep debt. Scientists tested the starving, sleepless flies for two markers of sleep debt: an enzyme in saliva and the flies'' ability to learn to associate a light with an unpleasant stimulus. Both tests showed that the starving flies were not getting sleepy.

"If you''re starving, you want to make sure you''re on the top of your game cognitively, to improve your chances of finding food rather than becoming food for someone else," said Matt Thimgan, a postdoctoral research associate.

Scientists also found that after sleep deprivation, flies with the LSD2 (Lipid storage droplet 2) mutation were less likely to sleep for longer periods of time and continued to score high on the learning test.

The study appears online Aug. 31 in PLoS Biology.