SLEEP SPINDLE: Rapid brain wave pulses, shown within the broken red lines, may block sound during sleep.
PEOPLE WHO HAVE TROUBLE sleeping in noisy environments may try strategies like earplugs or noise-canceling headphones to muffle the sound, but a new study may lead to ways to block disturbing sounds within the brain. In the Aug. 10 issue of Current Biology, an MGH research team reports finding a brain-wave pattern that predicts the ease at which sleep can be disrupted by noise. "Understanding the tools and techniques the brain naturally uses to promote stable sleep could allow us to harness and expand those responses to help people stay asleep in noisy environments," explains Jeffrey Ellenbogen, MD, chief of the MGH Division of Sleep Medicine.
When sound signals enter the brain, they pass through a structure called the thalamus on the way to the cortex, where they are perceived. Comunication between the thalamus and the cortex is reflected by fluctuations in the electrical signals detected by electroencephalogram (EEG) readings. Slow brain-wave patterns typical of deeper stages of sleep are known to be interspersed with brief, rapid pulses called spindles, which are believed to reflect activity that keeps sensory information from passing through the thalamus.
To test that hypothesis the team studied 12 healthy adult volunteers, each of whom spent three consecutive nights in the MGH Sleep Lab. EEGs taken during each night verified that participants with more frequent spindles in their brain waves were less likely to be awakened by a variety of sounds. The researchers now hope to investigate whether behavioral techniques, drugs or devices that enhance sleep spindles can help people stay asleep.
"It will be particularly important to apply these techniques to the care of hospitalized patients, who are often in pain, under stress and surrounded by noisy equipment," Ellenbogen says. "We need to work with hospitals around the country to develop solutions, targeting sounds like alarms to the people who need to hear them and not those who don't. Brain-based solutions like enhancing sleep spindles will likely have a role in these strategies." MGH co-authors of the Current Biology report are lead author Thien Thahn Dang-Vu, MD, PhD, and Scott McKinney, both of MGH Neurology.