Researchers at the University of Wisconsin-Madison have found that when a person is tired or sleep deprived, a part of the brain goes in a "sleep like state" even while rest of the brain remains awake.
The result can be silly mistakes, errors in performance or forgetfulness.
Even before you feel fatigued, there are signs in brain that you should stop certain activities that may require alertness, stated lead researcher Professor Chiara Cirelli, from the University of Wisconsin-Madison.
"Specific groups of neurons may be falling asleep, with negative consequences on performance," Cirelli added.
Certain brain cells take nap
Until now, scientists had thought that sleep deprivation affected the entire brain. But, the new research has found that there are certain group of neurons that go in sleep mode.
”It's very worrisome. It means that even before we have obvious global signs of sleepiness, there are more local signs of tiredness and they have consequences on performance.”--Lead researcher Professor Chiara Cirelli, from the University of Wisconsin-Madison.
To reach their findings, researchers studied the electrical activity of brains in rats who were sleep deprived.
As the rats had not slept for prolonged period, some brains cells took short nap while the rats were still awake and active. The longer they stayed awake, the more neurons dozed off.
Cirelli said, "This activity happened in few cells.
"For instance, out of 20 neurons we monitored in one experiment, 18 stayed awake. From the other two, there were signs of sleep -- brief periods of activity alternating with periods of silence."
Neuronal nap hinders performance
Also, researchers noticed that staying awake for a long period affected rats' concentration and dexterity. As a result, they started making mistakes.
To find this, scientists made rats perform a task of picking sugar pellets using their paws.
They found that rats with neuronal nap were were 37.5 percent more likely to drop or miss a pellet when grabbing it as compared to their counterparts.
“It's very worrisome. It means that even before we have obvious global signs of sleepiness, there are more local signs of tiredness and they have consequences on performance,” stated Cirelli.
She added that people should take sleep seriously. “When you're starting to nod off, it's too late. Even before that, there may be impairment. Respect your need for sleep."