Particular Brain Rhythm in Sleep Makes You More
Vulnerable to Disturbances03/03/11
THURSDAY, March 3 (HealthDay News) -- New findings about brain
rhythms could lead to the development of improved sleep treatments,
a new study suggests.
A team at Massachusetts General Hospital found that a brain
rhythm regarded as the emblem of wakefulness persists in a hidden
form during sleep, where it becomes more intense at certain times
-- something that appears to affect people's vulnerability to being
awakened by noise or other disturbances.
To test their theory, the researchers used computerized
electroencephalography (EEG) rhythms in 13 volunteers who slept --
or at least tried to -- three nights in the MGH Sleep Lab. At many
intervals throughout each night, the volunteers were exposed to 10
seconds of typical background noises, such as traffic or a ringing
telephone. The sounds were repeated at increasingly louder levels
until the EEG showed that sleep had been disrupted.
An analysis of the EEG measurements showed that the intensity of
the alpha signal predicted how easily volunteers could be disturbed
at the moment the measurement was taken, with a stronger alpha
signal linked to more fragile sleep.
"We found that the alpha rhythm is not just a marker of the transition between sleep and wakefulness but carries rich information about sleep stability," study author Scott McKinney, informatics manager at the MGH Sleep LAB, said in a hospital news release.
"This suggests that sleep -- rather than proceeding in discrete stages -- actually moves along a continuum of depth. It also opens the door to real-time tracking of sleep states and creates the potential for sleep-induction systems that interface directly with the brain," he added.
Although the alpha rhythm was discovered nearly 100 years ago,
researchers once thought it disappeared when sleep began because
they no longer saw it on an EEG. However, a technique called
spectral analysis can pick up subtle fluctuations in the alpha
rhythm during sleep levels that are not apparent when visually
inspecting an EEG.
The study appears in the journal
"This finding paves the way toward futuristic sleep treatments in which medication or other therapies are delivered moment-to-moment, only when needed, to protect sleep when the brain is most vulnerable but otherwise let natural brain rhythms run their course," study senior author Dr. Jeffrey Ellenbogen, chief of the MGH Division of Sleep Medicine, said in the news release.
"Learning more about the mechanism behind this association between the alpha rhythm and sleep fragility should lead to an even greater understanding of the factors that maintain sleep's integrity in the face of noise and other nuisances," he added.
The American Academy of Sleep Medicine offers a
list of healthy sleep habits.
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