Tuesday, 17 September 2019

Sound Asleep? Why Some People Can Sleep Through Noisesmall text medium text large text


Light sleepers who are easily awakened by noise have different brain rhythms than people who can sleep through it, a new study shows.

Researchers at Massachusetts General Hospital found that the number of brain rhythms called spindles produced during a quiet night determine whether a person will wake up on a noisy night in the future. The more spindles detected, the more likely it is that a person will sleep through noise.

"The general message is you can actually predict which person would be more sensitive to sounds during sleep, and one of the main predictors seems to be the quantity of spindles," the study's lead author Dr. Thien Thanh Dang-Vu told AOL Health.

The findings appear in the August 10 issue of the journal Current Biology.

Researchers said they set out to learn "what the brain does to promote stable sleep, even in the face of noise, and why some people are better at staying asleep than others," according to another author Dr. Jeffrey Ellenbogen.

Twelve healthy adults between the ages of 20 and 40 spent three consecutive nights in the Massachusetts General sleep lab. The first night was quiet, but during the second and third nights, participants were subjected to increasing levels of noise. EEG readings were taken to measure when they were sleeping and at what point they woke up.

The people examined maintained a steady number of spindles each night, the results showed, but those with a higher rate were less likely to be roused from sleep on the noisy nights than those whose brains had fewer spindles.

"We were surprised by the magnitude of the effect," Ellenbogen said in a summary of the findings. "It was so pronounced that we could see it after a single 'noisy' night."

Though people who have trouble sleeping through noise often use earplugs or headphones, the research indicates there may be a way to mute sound disturbances within the brain by getting it to generate more spindles, according to the scientists.

"We want to study behavioral techniques, drugs or devices that may enhance sleep spindles and see if they can help people stay asleep when confronted with noise," Ellenbogen explained.

Spindles are short, rapid pulses that come between the longer periods of slow brain wave patterns in the second and third stages of sleep. Stage 3 is REM sleep, the deepest and most difficult to wake someone from, said AOL Health's sleep expert Dr. Ronald Kotler.

"This may be something groundbreaking," he said of the new findings. "There are clues we're learning about the brain to help figure out who's having trouble sleeping and who's not."

Prior research shows that the brain activity responsible for creating spindles is the same type that blocks sound and other sensory information from passing through the thalamus. A handful of studies have analyzed what happens when noises are presented during spindle brain patterns, but haven't looked at the link between the quantity of those pulses and ability to stay asleep in a loud environment.

"The strength of the statistical significance was very robust," Dang-Vu told AOL Health. "I was happy to see our hypothesis was confirmed."

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