High Frequency of “Sleep Spindles” in Brain Make Sound Sleepers

Some people have no problem sleeping in the apartment next to the train tracks. Others wake at to footsteps and cricket chirps.

So-called “sleep spindles,” rapid pulses produced by the brain’s hypothalamus, appear to be why some people are prone to suffer from fractured sleep. A high frequency of sleep spindles can blanket the brain, protecting it from noise disruptions.

Researchers at Harvard University say their research suggests light sleepers don’t produce enough “sleep spindles.” The study was published in the August 9 issue of Current Biology.

A group of 12 subjects volunteered to spend three consecutive nights in a sleep laboratory. None of the volunteers had a history of sleep disorders.

After one night of sleeping in silence, the subjects spent two more nights suffering through a barrage of overnight noise interruptions. The sounds ranged from traffic to toilets flushing. The sounds played at 30-second intervals, increasing in volume until researchers noted a reaction.

EEG readings showed people who reacted to the fewest disruptions had produced more sleep spindles, even on the quiet night. Most of the spindles were produced during the second and third stages of slow wave sleep.

Participants often didn’t realize their sleep had been interrupted. As previous studies suggest, environmental sleep interruptions often go undetected and can lead to daytime fatigue even if you thought you had a full night of sleep.

Researchers say their discovery will hopefully lead to new ways to help light sleepers get uninterrupted rest in noisy places such as hospitals.

Image by Amanda G.