Scientists find we really can learn while we sleep September 16, 2012

Sleep learning experiments are especially difficult conduct, researchers have to make sure the participants are actually asleep.   The team at the Weizmann Institute of Science exposed sleeping subjects to a tone followed by a smell, neither of which woke them up.   The odor was either pleasant of unpleasant – generating a deep or a shallow breath – and each was associated with a particular tone.   When the corresponding tones were replayed, the participants either elicited a deep or shallow breath, without the presence of the odor.   When exposed to tones that had been paired with pleasant odors, they sniffed deeply, while the second tones – those associated with bad smells – provoked short, shallow sniffs.