Don't we all love our sleep? It's so utterly cleansing... if we are
lucky. But some of us don't sleep well or not long enough for sleep to
"knit up the ravell'd sleeve of care.*" Sleep researchers at five institutions looked to brain activity in this study of
the secrets of a good night's sleep.
Specifically, what they studied was the relationship of noise sensitivity to sleep. During sleep, sensory input is modulated through spontaneous signals from our brain's thalamus to the cortex.
The Brain: Image from TheBrain.mcgill.ca
These signals can be measured by EEG (electroencephalogram) readings and they show up as bursts of brain activity called spindles.
Studying the sleep patterns of 12 healthy adults during one full night of sleep, the team of researchers representing Harvard Medical School, Massachusetts General Hospital, University of Liege (Belgiium), Brigham and Women's Hospital, and the Cambridge Health Alliance established the rate per minute of spindle activity for each volunteer during stages 2 and 3 of Non-REM sleep. During this first night of observation, quiet was maintained in the sleep labs.
During the following two nights, the researchers introduced noises that commonly occur during sleep, like air and road traffic and ringing telephones. In response to these noises, those who had higher spindle rates under quiet conditions, were less likely to be aroused from sleep by the intermittent noises. Those with normally lower spindle rates, were more likely to have their sleep interrupted when noises were introduced.
Spontaneous spindle detection: © Current Biology
While the researchers involved in this study, Spontaneous brain rhythms predict sleep stability in the face of noise, published in Current Biology, learned that the frequency of spindle activity was significant to a good night's sleep, no one seems to know how to increase that activity with intervention.
Perhaps, though, the spindle findings will lead to behavioural or pharmaceutical interventions that can help more of us just experience a good night's sleep!
*Macbeth, Act 2, Scene 2
Current Biology via Business Week