Light sleeper

Light sleeper or sleep through anything? Thank (or blame) the brain

By Stephanie Steinberg, USA TODAY

sleep light


Why can some people sleep through car alarms and thunderstorms when others wake up at the sound of footsteps?


Researchers believe they've found the answer tucked in sleep spindles, or bursts of brain activity that occur only during sleep.

A study released today in Current Biology describes how sleep spindles protect the brain from noise disruptions. The study found that the more spindles the brain produces, the more likely a person will stay asleep when exposed to various sounds.Spindles are produced by the thalamus — a structure in the brain that conveys senses, like sound, to the parts of the brain that perceive and respond to sensory information.

Researchers have speculated that the spindle is responsible for blocking sounds, but this is the first study to prove the theory, says Jeffrey Ellenbogen, chief of the Division of Sleep Medicine at Massachusetts General Hospital. The information can be used to determine who's "vulnerable" to sounds at night versus who can "sleep deeply," he says.


For three consecutive nights, researchers monitored the brain patterns of 12 volunteers while they slept. The participants, ages 20-46, had no prior sleep disorders.


The first night was quiet, but noises such as a ringing telephone, people talking and a toilet flushing were added in the second and third nights.


Results showed that participants who produced more spindles had a higher resistance to waking from sounds. But researchers don't know why some people generate more spindles than others.


Ellenbogen, an assistant professor of neurology at Harvard Medical School, plans to do further research to answer this question. He also hopes to create a drug or technological device that helps the brain produce natural sleep spindles.


The long term goal is to create a "utopia for sleepers both in the home, hotel or wherever people choose or have the need for sleep," he says.


One of the areas of interest includes noisy hospital environments where patients constantly hear alarms, beeps and the hum of machines. The sounds emanate from equipment intended to help patients, but they don't benefit if they're disrupted from sleep, Ellenbogen says.


Each year, at least 40 million Americans suffer from sleep disorders — including insomnia, sleep apnea and restless legs syndrome — according to the National Institute of Neurological Disorders and Stroke.

But the majority of Americans do not get enough sleep, says Lisa Shives, spokeswoman for the American Academy of Sleep Medicine. Part of the problem is that people put off sleep in favor of getting work done at night, she says.

"Nobody really closes the office door anymore," she says. "They stay up and sleep deprive themselves."


For people who have trouble staying asleep, Shives recommends taking a hot bath or shower one hour before bed. This makes the body temperature rise and then fall, which causes a drowsy effect. People should also avoid eating foods with a lot of sugar.


"The last thing you want to do right before bed is shoot your blood sugar up," she says.


The study was funded by grants from the Academy of Architecture for Health, the Facility Guidelines Institute and the Center for Health Design.

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