Neurons take a break during stage 2 sleep
The time off prevents interruptions that could wake a person up
Even neurons need quiet time. A new study shows the brain cells take time out while you sleep, preventing you from waking up at the drop of a hat or other nonthreatening object.
For decades, scientists have been measuring electrical activity in the brain during sleep with electroencephalograms, or EEGs. Researchers easily recognize the hallmark dips and blips of each stage of sleep, but what brain cells are doing to produce the signals hasn’t been apparent.
Now, a new study in the May 22 Science shows that a prominent electrical signal of stage 2 sleep, called the K-complex, indicates downtime for neurons. The quiet periods could help people ignore distractions, such as sounds and touches, and stay asleep, the researchers report.
K-complexes appear as sharp dips in EEG tracings. The events happen shortly after a person falls asleep, during a period of what’s called non-rapid eye movement sleep when people are transitioning from light sleep into the heaviest periods of deep sleep. This period of stage 2 sleep is one of four ever-deepening stages of non-REM sleep. People spend most of the night in stage 2 sleep, which is characterized by K-complexes as well as the distinctive brain wave signal known as spindles.