Rose scent activates memory during sleep, study says

Research also gives clearer view of how the brain works when a person sleeps


FLOWER POWER: Inhaling the rose fragrance during deep sleep intensifies the transfer of memories in the brain, say researchers. -- REUTERS


WASHINGTON - PEOPLE who want to learn things might do better by literally stopping to smell the roses, according to German researchers.

They have found that the rose scent can be used to reactivate new knowledge in the brains of people while they sleep, enabling them to remember better this information later.

The results of the new study, which appeared yesterday in the journal Science, give a clearer picture of what the slumbering brain does with newly learned material and may help scientists develop memory treatments directed at the deep-sleep stage.

The study is the first rigorous test of the effect of odours on human memory during sleep.

In the study, German neuroscientists exposed groups of students to bursts of rose scent as they played a memory game in which they had to match pairs of cards on a computer.

Volunteers then received similar bursts of the fragrance during various stages of sleep. Those who received the rose scent outperformed others by 15 per cent when they replicated the exercise the following day, according to the study.

Although the presence of the scent was important, the stage of sleep at which it was administered was crucial too, the researchers said, in a finding that will add to the debate over whether people 'learn' in their sleep the way some animals have been shown to.

The brain is thought to process newly acquired facts, figures and locations most efficiently in deep sleep. These so-called slow-wave periods usually occur within the first 20 minutes or so after a person head meets the pillow and may last an hour or longer, then recur once or a few times later in the night.

Pictures taken of the volunteers' brains using magnetic resonance imaging while they slept showed that the hippocampus, the part of the brain associated with learning new things, was activated when the volunteers were exposed to the odour during deep sleep. But no effect was observed during the rapid-eye-movement sleep strage.

'We would expect spontaneous reactivation driven by the slow-wave sleep, but by presenting the rose odour cues we intensified this activation and enhanced the transfer of these memories,' said Dr Jan Born, a neuroscientist at the University of Luebeck and an author of the study.

NEW YORK TIMES, BLOOMBERG, REUTERS