Scent of a Memory

"Scientists studying how sleep affects memory have found that the whiff of a familiar scent can help a slumbering brain better remember things that it learned the evening before. The smell of roses — delivered to people’s nostrils as they studied and, later, as they slept — improved their performance on a memory test by about 13 percent.

The new study, appearing today in the journal Science, is the first rigorous test of the effect of odor on human memory during sleep. The results, whether or not they can help students cram for tests, clarify the picture of what the sleeping brain does with newly learned material and help illuminate what it takes for this process to succeed.

Researchers have long known that sleep is crucial to laying down new memories, and studies in the 1980s and ’90s showed that exposing the sleeping brain to certain cues — the sound of clicking, for instance — could enhance the process. But it is only in recent years that scientists have begun to understand how this is possible.

“The idea didn’t get any traction with scientists back then, because it didn’t make sense,” said Dr. Robert Stickgold, an associate professor of psychiatry at Harvard, who was not involved in the research. The new study, Dr. Stickgold added, “shows not only that sleep is important for declarative memory, but also allows us to look at exactly when and how this process might happen.”

- Study Uncovers Memory Aid: A Scent During Sleep