Awake? Maybe not completely

SMALL PRINT:IS YOUR BRAIN awake or asleep? Or perhaps both? New findings in rats show that during sleep deprivation, some brain cells can take a nap even though the animal appears to be awake.

Using electroencephalography, or EEG, the scientists could pick up changes in the electrical activities of brain cells as the animals moved around.

From that, they saw that during sleep deprivation – they gave the rats toys to help keep them from nodding off – the animal would be visibly awake in its behaviour, and on a global level the electrical activity in the brain was flashing “awake”. But when they looked closely, it appeared that locally, some brain cells were going offline and acting like they were asleep.

All very well, but how might these patches of neuronal napping affect performance? The researchers found that as neurons hit the snooze button, the animals fared worse on learning tasks.

"Thus, although both EEG and behaviour indicate wakefulness, local populations of neurons in the cortex may be asleep, with negative consequences for performance," they wrote in the journal Nature.

“Such tired neurons in an awake brain may be responsible for the attention lapses, poor judgment, mistake-proneness and irritability we experience when we haven’t had enough sleep, yet don’t feel particularly sleepy,” said co-author Giulio Tononi of the University of Wisconsin-Madison in a statement.