A new study in rats is shedding light on how sleep-deprived lifestyles might impair functioning without people realizing it. The more rats are sleep-deprived, the more some of their neurons take catnaps — with consequent declines in task performance. Even though the animals are awake and active, brainwave measures reveal that scattered groups of neurons in the thinking part of their brain, or cortex, are briefly falling asleep, scientists funded by the National Institutes of Health have discovered.