NyTimes: Rose During Sleep Improves Memory

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Can anyone pass the bottle of rose essential oil, please?

Misty L. Trepke

http://health.

 

 

Study Uncovers Memory Aid: A Scent During Sleep

 

http://www.nytimes.com/2007/03/09/science/09sleep.html?

_r=1 & em & ex=1173675600 & en=ab5f8ca56edc1d15 & ei=5087%0A & oref=slogin

 

A participant sleeping in a laboratory with a nasal mask attached

for olfactory stimulation. Bottles on the left contain various

scents.

 

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By BENEDICT CAREY

Published: March 9, 2007

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. "

 

In the study, neuroscientists from two German institutions, 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 masks they

wore. The researchers delivered the fragrance in bursts because the

brain 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 (or REM)

sleep.

 

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 longer, then recur once or more 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 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 just before sleep or in REM sleep rather than in deep

slumber, and their improvements were not due to practice, the study

found.

 

The study's results could eventually help doctors improve patients'

memory by devising treatments directed at deep sleep. As they age,

people spend less and less time each night in such sleep, and

existing sleep medications do not generally increase it. But

pharmaceutical companies are investigating compounds that do so.

 

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 in that

communication, the study's authors argue, is that the cortex is

telling the hippocampus to reactivate the same neurons that fired

when a particular fact was noticed or learned. The hippocampus does

so, encoding the firing sequence in the cortex and thereby

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, " said Dr.

Jan Born, a neuroscientist at Lübeck who undertook the study with

Björn Rasch, Christian Büchel and Steffen Gais.