According to recent study involving rats, sleep deprivation is a shared problem amongst all animals. The study, completed by neuroscientists at the University of Wisconsin, Madison, showed that problem-solving regions of the animal brain fall into a state called “local sleep,” observed in sleep-deprived humans and rats. This phenomenon suggests that parts of your brain might be dozing, even though you fell awake and alert. The study details will be published this week in Nature.
Giulio Tononi, co-author of the sleep study, said that when sections of the rats’ brains entered the state of “local sleep,” “you couldn’t tell that the rats are in any way in a different state of wakefulness.” The rats’ behaviors initially suggested that they were fully awake, as the overall brain activity was normal. However, then asked to perform a challenging task, such as using their paws to reach sugar pellets, the sleep-deprived rats struggled. The phenomenon is “not just an interesting observation of unknown significance,” Tononi said, “it actually affects behavior- you make a mistake.”
Researchers used electroencephalogram (EEG) readings to record the electrical activity in the rats’ brains. Sleep is usually identified on an EEG by “slow waves,” regular up and down patterns characteristic of non-rapid eye movement sleep. Humans and rats spend about 80% of their sleep time in non-REM. When researchers analyzed the EEGs of the sleep deprived rats, they saw that overtired rats’ cerebral cortices, the part of the brain responsible for complex brain function, entered a slow wave stage period, similar to actual sleep.
The exact purpose of sleep is not known by scientists. Tononi believes that overworked neurons are taking break, similar to a reset button, during slow-wave sleep. “If this hypothesis is correct, that means that at some point (if you’re putting off sleep), you’re beginning to overwhelm your neurons- you are reaching a limit of how much input they can get,” he said. Neurons then “take the rest, even if they shouldn’t,” and the stupid mistakes we sometimes make become inevitable.
The U.S. Centers for Disease Control and Prevention says humans need seven to nine hours of sleep every night. If you don’t have at least a sufficient amount of sleep, you might be “sleeping” through your day without even realizing it. “You don’t need to feel sleepy to screw up,” Tononi said. “Even if you may feel that you’re fit and fine and holding up well, some parts of your brain may not be…and those are the ones that make judgments and decisions.”
Photo by Luke Culig for Alamy
