Familiar scents improve memory during sleep

[Al-khiyal]

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. A rose bouquet — delivered to people's nostrils as they studied and, later, as they slept — improved their performance on a memory test by almost 15 percent.

The report, appearing Friday in the journal Science, is the first rigorous test 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 studied material, and of 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 cues associated with learning — 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 Robert Stickgold, a psychiatrist at Harvard University, who was not involved in the research. He added that the new study "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."

In the study, neuroscientists from the University of Lübeck and the University Medical Center, Hamburg-Eppendorf, had groups of medical students play a version of concentration, memorizing the location of card pairs on a computer screen. Upon learning the location of each pair, the students received a burst of rose scent in their noses, through a mask they wore. The researchers delivered the fragrance in bursts because the nose quickly adjusts to strong smells in the air, and begins to ignore them.

The students went to sleep about a half hour later, with electrodes on their heads tracking the depth of their slumber. Neuroscientists divide sleep into stages, including deep or slow-wave sleep and the shallow, dream-rich state called rapid-eye-movement sleep, or REM.

The brain is thought to process newly acquired facts, figures and locations most efficiently in deep sleep. This restful state usually descends within the first 20 minutes or so after head meets pillow, and may last an hour or more, then recur later in the night. The researchers delivered pulses of rose bouquet during this slow-wave state; the odor did not interrupt sleep, and the students said they had no memory of it.

But their brains noticed, and retained an almost perfect memory of card locations. The students scored an average of 97 percent on the card game, compared with 86 percent when they played the concentration game and slept without being perfumed by nighttime neuroscience fairies.

The students did not get the same boost when they received bursts of the fragrance before falling asleep, and their improvements were not due to practice, the study found.

Previous research has shown that regions of the cortex, the thinking and planning part of the brain, communicate during deep sleep with a sliver of tissue deeper in the brain called the hippocampus, which records each day's memories. What is most likely happening, the study's authors argue, is that the cortex is reactivating the same set of neurons that fired when a particular fact was noticed or learned. The hippocampus then encodes that firing sequence back in the cortex, consolidating the memory.

"We would expect spontaneous reactivation driven by the slow-wave sleep, but by presenting the rose odor cues we intensified this activation and enhanced the transfer of these memories into the neocortex," said Jan Born, a neuroscientist at Lübeck and an author of the study. His co-authors were Bjorn Rasch, Christian Büchel and Steffen Gais.

Olfactory sensing pathways in the brain lead more directly to the hippocampus than visual and auditory ones. That may be why smells can be linked so closely to memory.

To check their reasoning, the researchers took magnetic resonance images of some of the students' brains during their rose-scented slumber. As predicted, regions of the cortex became noticeably more active, as did the hippocampus.

Familiar scents improve memory during sleep

[Al-khiyal]

Science Magazine

[Bent_Bladi]

I'm gonna try this technique for my next biology exam... Should I tie a rose to the ceiling and have it dangle under my nose??

Thanks Al-k --- I'm bookmarking that magazine's site

[liberte]

Any excuse to have more roses in the house is fine by me!

Slightly off-topic (but still rose-related)

Aromatherapy A-Z: Rose

Of the estimated 5,000 or more species of roses that grace our environment, the damask rose (Rosa damascena) and the cabbage rose (Rosa centifolia) are the most fragrant, and they are the two primary roses that produce essential oils for aromatherapy. At one time, the red rose (Rosa gallica) supposedly yielded rose oil as well, but it is so rare as to be essentially unavailable today.

Native to the Orient, Persia (now Iran) and Syria, these members of the Rosaceae family are now cultivated in the temperate regions of Bulgaria, China, France, India, Italy, Morocco, Russia, Tunisia and Turkey. These bushy deciduous shrubs grow three to six feet tall or taller. Their sweet-scented blossoms range in color from white to pink to red.

Steam-distilling over 60,000 freshly picked roses will yield only one ounce of rose oil. Pale yellow or deeper yellow rose oil, or rose otto, has a rich, sweet and spicy floral fragrance. Rose absolute, a reddish orange oil with a heavier, sweeter scent, is extracted with solvents. Because residues of solvent may remain in rose absolute, rose oil is more desirable for aromatherapy purposes.

Beauty Benefits

Rose oil benefits all skin types, especially mature, sensitive, dry or damaged skin. It helps restore the moisture balance and smoothes wrinkles. It constricts tiny blood vessels, thus helping to diminish the redness of broken capillaries.

Emotional Effects

Rose oil soothes the emotions. It lifts depression, eases anxiety, elevates spirits and reduces stress and tension. It stabilizes mood swings, particularly if they are related to postnatal depression. It calms the nerves and helps to overcome insomnia. Rose oil can ease grief and subdue sadness. It helps to eliminate feelings of disappointment, jealousy and resentment, and can help dissolve emotional blocks standing in the way of happiness. Rose oil symbolizes purity and innocence, yet it is a sensual and stimulating aphrodisiac. It promotes feelings of love and may help in overcoming impotence or frigidity.

Rose - Aromatherapy - iVillage Beauty Body Spa