单项选择题

案例分析题How many times do you wake during the night Do the slightest disturbances—the sound of a toilet flushing, or the TV in the next room—rouse you from sleep, while your partner slumbers soundly through a thunderstorm
It turns out that some people’s brains are better than others’ at blockading (阻碍) the constant incoming flow of environmental stimuli during sleep, and in a new study, scientists have identified and measured the process. They hope that one day they will be able to manipulate this ability in order to give lighter sleepers a better night’s rest.
Ambient (周围的) sound is the most common cause of sleep interruption, since even during sleep the brain must actively receive sensory information. But as it continually monitors stimuli (刺激) from the environment in order to protect against threats, the brain also actively blockades them to allow body and mind to recharge and rest during sleep. Now, for the first time, sleep researchers led by neurologist Dr. Jeffrey Ellenbogen, have isolated the brain wave pattern that predicts where an individual’s brain has struck that balance between those two demands—a window into how likely noises are to wake people from deep sleep.
"People currently working on how noise disrupts sleep typically look at it from two perspectives," says Ellenbogen. "They look at the source of the sound or—so public policies attempt to stop airplanes from flying at certain times or over certain areas they address the path of the sound, at things like double-paned windows or ear plugs. I’m adding a third perspective—the brain. Because the key part of normal healthy sleep is being able to block the response to sounds."
For the three-night study, Ellenbogen’s group invited 12 volunteers who reported being deep and healthy sleepers into a sleep lab with a comfy queen-size bed that was outfitted with enormous speakers at the headboard. The researchers recorded the participants’ brain waves as they slept normally the first night, and then again on subsequent nights as they were bombarded with 14 different noises which were played at progressively louder volumes.
Ellenbogen paid particular attention to the patterns generated by the thalamus(丘脑), a region deep in the brain that processes incoming visual and auditory stimuli. He found that the number of pulses, known as sleep spindles, generated by thalamus, varied among the sleepers. Those with the highest number of spindles were able to sleep through more sounds without waking, compared with those whose brains showed fewer spindles. More spindles meant they were more likely to be protected from sleep disruption.
What can the brain wave pattern isolated by neurologist Dr. Jeffrey Ellenbogen tell us（）