Sleep Matters

Source: Mashable, Dec 2013

Sleep deprivation affects the brain in multiple ways that can impair judgment, slow reaction times and increase the likelihood of drifting off during monotonous tasks.

Studies have shown that exhausted people do worse on tests of memory and have more trouble learning. Tired basketball players sink fewer free throws. Even golfers who fail to get enough shut-eye take more strokes to finish a round.

When it comes to accidents, sleep matters because failure to get enough rest hampers functioning of the brain’s frontal lobes, which are responsible for executive judgment, or the ability to pay attention and make good decisions.

In overtired people, Howell said, imaging studies have shown that there is less blood flow to these areas in the front of the brain and brainwaves there move more slowly.

The result is a compromised ability to respond to things, along with a faulty tendency to do things you shouldn’t have done. When the frontal lobes aren’t working efficiently, people also have more difficulty paying attention during boring tasks, such as driving a car on a highway or operating a morning commuter train.

Recently, scientists have begun to piece together an even more nuanced understanding of why sleep is so restorative. In a study published in Sciencethis fall, Nedergaard and colleagues injected mice with a green dye that allowed them to track the movement of cerebrospinal fluid, the liquid that surrounds the brain.

As our brains do their work throughout the day, previous work had shown that cerebrospinal fluid collects the waste products of normal metabolism and functioning. Then, a network of tiny channels works like a dishwasher to regularly flush out the dirty fluid and send it to the liver for detoxification.

The new study found that sleeping facilitated the flushing of this toxic fluid, which was much slower to drain in sleep-deprived rodent brains. Nerve cells are very sensitive to the presence of waste, Nedergaard said. When surrounded by contaminated fluid, communication at the cellular level likely slows down.

“What we described is that this microscopic cleansing system turns on as soon as we fall asleep and washes the brain clean,” Nedergaard said.

“From our standpoint, when you’re sleep deprived, you get a dirty brain.”

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