研究表明睡眠清除大脑垃圾_BEC初级作文

研究表明睡眠清除大脑垃圾

Although as essential and universal to the animal kingdom as air and water, sleep is a riddle that has baffled scientists and philosophers for centuries. Drifting off into a reduced consciousness seems evolutionarily foolish, particularly for those creatures in danger of getting eaten or attacked.

One line of thinking was that sleep helps animals to conserve energy by forcing a period of rest. But this theory seems unlikely since the sleeping brain uses up almost as much energy as the awake brain, Nedergaard said.

Another puzzle involves why different animals require different amounts of sleep per night. For instance, cats sleep more than 12 hours a day, while elephants need only about three hours. Based on this newfound purpose of sleep, neuroscientist Suzana Herculano-Houzel speculates in a commentary that the varying sleep needs across species might be related to brain size. Larger brains should have a relatively larger volume of space between cells, and may need less time to clean since they have more room for waste to accumulate throughout the day.

Sleep does play a key role in memory formation — mentally going through the events of the day and stamping certain memories into the brain. But sleeping for eight hours or more just to consolidate memories seems excessive, Nedergaard said, especially for an animal such as a mouse.

Last year, Nedergaard and her colleagues discovered a network that drains waste from the brain, which they dubbed the glymphatic system. It works by circulating cerebrospinal fluid throughout the brain tissue and flushing any resulting waste into the bloodstream, which then carries it to the liver for detoxification.