People Can Learn While They're Asleep, Study Finds

People are able to learn new information while they sleep, a study has found. Unfortunately, what the study's volunteers learned is much simpler than what most people might wish for. Researchers at the Weizmann Institute of Science in Israel taught 55 study volunteers to associate certain sounds with certain smells, Nature News reported. The study appeared in a journal by Nature News' publisher, Nature Neuroscience.

Using classical conditioning, also known as Pavlovian conditioning, the Weizmann researchers played certain sounds while wafting different odors to the volunteers while they were asleep. The researchers used pleasant smells, such as deodorant and shampoo, and unpleasant smells, such as rotting fish and carrion. The scientists found that the sleepers breathed shallowly when exposed to the unpleasant smells, but sniffed in deep when exposed to the pleasant smells.

Once they awakened, the sleepers didn't remember anything about the sound-smell conditioning. Yet when certain sounds were played — without the accompanying smells — the volunteers would sniff either shallowly or deeply, depending on the smell with which the sound was originally associated.