Frontier: Temporary insomnia may lead to learning troubles

by Aalok Mehta

January, 2009

Even a few nights of sleeplessness can have long-term consequences on learning and memory, suggests new research looking into “sleep fragmentation”—the fractured, intermittent slumbering that afflicts many insomniacs.

Dennis McGinty, a professor of psychiatry at the University of California, Los Angeles, and his colleagues found that rats continually deprived of sleep had learning problems even weeks after returning to normal sleep patterns.

To conduct the study, the team roused rats after only a few minutes of shut-eye for 12 days. When placed in a maze after two weeks of normal sleep, the rats had more difficulty locating the exit than did normally dozing animals, the researchers found. When the exit was shifted midexperiment, the sleep-disturbed rats also took more time finding the new location. McGinty’s team had previously shown that sleep fragmentation disrupts the formation of new neurons in the rat hippocampus. Because new neurons take four weeks to develop and mature, the scientists suggest that the disrupted learning may be a direct result of this slowdown in adult neurogenesis.

“The most prevalent form of sleep disorders [in people] are sleep fragmenting disorders” such as obstructive sleep apnea and insomnia, McGinty said at a press briefing where he first presented the new findings. Normal aging also causes some sleep fragmenting, offering a possible explanation for the mental declines that occur as people get older, he added.