Are You a Light or Heavy Sleeper?

Why is it that some people can sleep through almost anything, while others need earplugs and white noise to get through the night? Researchers think your ability to cope with disruptive sounds while sleeping has something to do with how your brain is wired.

In your brain, sound passes through the thalamus as it travels to the cortex. These are the deeper sections of the brain, where sound signals are recognized. Brain wave patterns shown on an electroencephalograph (EEG) indicate to researchers just how these two brain structures communicate during different stages of sleep. During the second and third stages of sleep, an EEG normally picks up slow wave patterns interrupted by rapid pulses known as spindles.

The same brain mechanism that produces these spindles also helps block outside stimulation by preventing noise from reaching the thalamus. The number of spindles you produce during these stages of sleep determines whether or not you are bothered by noise at night, according to a small study published in an August 2010 issue of the professional journal Current Biology.

The researchers looked at the EEG patterns of twelve volunteer sleepers during one quiet night and two consecutive noisy nights, when they were subjected to increasing levels of typical sounds such as street noises and telephones ringing. They found that those sleepers who had produced more spindles on the quiet night were less likely to wake up during noisy nights.

In some cases, the sleepers who were disturbed by noise did not remember being aroused as a result. To the researchers, this only means that noise at night may affect quality of sleep more than some people realize.

Spindles are only produced during sleep, and it is not known why some people produce more than others. Now, however, it is possible to use brain wave patterns to help predict who is more easily disturbed by noise at night and begin to develop techniques, medications and other solutions to help those people get a good night's sleep when noise is inevitable or uncontrollable.



Dang-Vu, T, et al. "Spontaneous Brain Rhythms Predict Sleep Stability in the Face of Noise." Current Biology: 20(5);R626-R627 10 Aug 2010 Web. 16 Nov 2010.