Washington: Scientists claim to have
cracked the secrets of a good night`s sleep -- as to why some
could sleep peacefully despite the noise of modern life while
others stir at the sound of footsteps and cricket chirps.
A team at Harvard Medical School claims that a section
of the brain, known as thalamus, plays a key role in blocking
out sound during sleep and it appears to be more effective in
Normally brainwaves slow down during rest, but brain
still generates brief energy bursts called sleep spindles.
Lead scientist Jeffrey Ellenbogen said: "The thalamus
is likely preventing information from getting to areas of the
brain that react to sound. A sleep spindle is a marker of this
blockade. The more spindles your brain makes, the more likely
you`ll stay asleep, even if confronted by noise."
For the study, the scientists analysed 12 healthy
volunteers at a sleep clinic over the course of three nights.
They were monitored each night using an electroencephalograph
which records the electrical activity of the brain.
The first night was quiet but during the second and
third nights, volunteers were confronted with the sounds of
telephones ringing, road and air traffic noises and the beep
of hospital equipment.
The team detected patterns known as sleep spindles
which are thought to block out the effects of sound and other
sensory information passing through the brain.
Individuals with the highest rates of spindles on
the quiet night were less likely to be woken by noises on the
second and third nights, and some were not even aware their
sleep had been disrupted, Ellenbogen said.