Good news for dozy students at the back of the class – scientists have shown that it is possible to learn new things while asleep.
A study, published in the journal Nature Neuroscience, found that volunteers were able to recall something they had heard while slumbering when they awoke the next day, even though they had no memory of being taught.
The experiment focused on teaching the brain to associate particular sounds and smells – as people can be exposed to these stimuli without waking up. Researchers monitored the sleeping volunteers' nostril movements and found that the pleasant scent of shampoo, for instance, led to deep intakes of air, while the unpleasant odour of rotting fish caused the volunteers to briefly stop inhaling.
As the night progressed, the sleeping individuals learnt to associate the sound of particular tones with certain smells. For instance, they breathed more deeply when played the positive tone even when no smell was present.
"The next day, the now awake subjects again heard the tones alone – with no accompanying odour. Although they had no conscious recollection of listening to them during the night, their breathing patterns told a different story," said a spokesman for the Weizmann Institute of Science in Israel. "When exposed to tones that had been paired with pleasant odours, they sniffed deeply, while the second tones – those associated with bad smells – provoked short, shallow sniffs," he added.
Anat Arzi, a research student at Weizmann who carried out the study, said: "The common knowledge is that although the sleeping brain can process, consolidate and strengthen information, it cannot learn new information. We showed that it could." He added: "There will be clear limits on what we can learn in sleep, but I speculate that they will be beyond what we have demonstrated."
The researchers intend to continue investigating other types of brain processing in various altered states of consciousness such as sleep and coma.