Scientists are providing a fuller understanding of the essential role that sleep plays in brain health, identifying an abrupt transition at about 2.4 years of age when its primary purpose shifts from brain building to maintenance and repair.
Researchers on Sept. 18 said they conducted a statistical analysis on data from more than 60 sleep studies. They looked at sleep time, duration of rapid eye movement (REM) sleep, brain size and body size, and devised a mathematical model for how sleep changes during development.
There are basically two types of sleep, each tied to specific brain waves and neuronal activity. REM, with the eyes moving quickly from side to side behind closed eyelids, is deep sleep with vivid dreams. Non-REM sleep is largely dreamless.
Photo: Reuters 照片：路透
During REM sleep, the brain forms new neural connections by building and strengthening synapses — the junctions between nerve cells, or neurons — that enable them to communicate, reinforcing learning and consolidating memories. During sleep, the brain also repairs the modicum of daily neurological damage it typically experiences to genes and proteins within neurons as well as clearing out byproducts that build up.
At about 2.4 years of age, the findings showed, sleep’s primary function changed from building and cutting connections during REM sleep to neural repair during both REM and non-REM sleep. “It was shocking to us that this transition was like a switch and so sharp,” said Van Savage, a UCLA professor of ecology and evolutionary biology and of computational medicine who is a senior author of the research published in the journal Science Advances.
REM sleep declines with age. Newborns, who can sleep about 16 hours daily, spend about 50 percent of their sleeping time in REM, but there is a pronounced drop-off at around 2.4 years. It drops to about 25 percent by age 10 and to about 10 percent to 15 percent around age 50. “Sleep is required across the animal kingdom and is nearly as ubiquitous as eating and breathing,” Van Savage said. “I’d say it is a pillar of human health.”(Reuters)
科學家近日提出更完整的理論，進一步闡釋睡眠對大腦健康扮演不可或缺的角色。科學家確認，兒童大腦約在二歲五個月時會發生突然的轉變。此時，睡眠的首要目的從大腦發育轉變成維護與修復。
研究人員於九月十八日指出，他們對超過六十個睡眠研究提供的資料進行統計學分析。他們觀察睡眠時間、快速動眼期的持續長度、大腦和身體尺寸，並且設計出一套數學模型，研究睡眠在成長過程中會如何發生變化。
基本上，睡眠分成兩種類型，各自和特定的腦波與神經元活動密切相關。在快速動眼期，眼球會在緊閉的眼皮後方快速左右移動，進入深層睡眠，此時做的夢也特別清晰。非快速動眼期則大多是無夢的。
在快速動眼期睡眠中，大腦藉由建立以及強化「突觸」──也就是神經細胞（或稱神經元）的相接處──形成新的神經連結，讓它們得以互相交流，藉此加深學習並且鞏固記憶。在睡眠期間，大腦也會修復平日受到的少量神經系統損傷──通常發生於基因和神經元裡面的蛋白質──同時清除累積的副產物。
研究顯示，在大約二歲五個月左右，睡眠的首要功能會發生改變，從快速動眼期睡眠中持續建立並且切斷連結，轉變成在快速動眼期以及非快速動眼期這兩個睡眠期間進行神經修復。這份研究近日發表於期刊《科學進展》，其資深作者范‧薩維奇指出：「我們很訝異，這個轉變就像是切換開關一樣，非常突然。」范‧薩維奇是美國加州大學洛杉磯分校生態學和演化生物學教授，同時也是計算醫學教授。
快速動眼期睡眠會隨著年紀增長而減少。新生兒一天可以睡到十六個小時，其中大約一半的睡眠時間都花在快速動眼期。然而，大概到兩歲五個月的時候，快速動眼期就會顯著降低。到了十歲，快速動眼期約佔睡眠時間的百分之二十五；到五十歲時，快速動眼期更衰退到睡眠時間的百分之十到十五左右。「睡眠在整個動物界都是必要的活動，就跟進食和呼吸一樣無所不在。」范‧薩維奇表示：「我會說，睡眠是人類健康的支柱。」（台北時報章厚明譯）
A: China’s animated blockbuster “Ne Zha 2” also smashed a box office record recently. B: It’s No. 7 among the world’s best-selling films, grossing more than US$2 billion globally. A: I t has even become the world’s highest-grossing animated film, while the political metaphors in it are causing controversy. B: But who is Ne Zha anyway? A: Ne Zha, often spelled as “Nezha,” is actually a mythical teenage deity with superpowers. A: 中國動畫片《哪吒2》最近也打破紀錄。 B: 該片已衝上影史票房排行榜第7名，全球狂賣超過20億美元。 A: 聽說它甚至是全球最賣座的動畫片，影片中的政治隱喻卻引爆爭議！ B: 但哪吒是誰？ A: 哪吒的名字常被拼成「Nezha」，是神話中具有超能力的青少年神明。
People desire a sense of purpose in their lives, but they often remain idle unless they have a clear reason to act. This concept is illustrated by the retirement paradox. People work hard to prepare for a future without work but find life meaningless after achieving that goal. A study was carried out to determine if a reason, even a minor one, could encourage idle people to take action. __1__ Upon finishing the first, they were instructed to drop it off at a location either right outside the room or at a spot farther away, which would take around
Microsoft on Feb. 28 announced it was retiring Skype, the online voice and video call pioneer that the tech titan acquired in 2011. “Starting in May 2025, Skype will no longer be available,” said a post from Skype support on X, directing users to sign into Microsoft’s Teams platform for further use of its services. Skype was founded in 2003 by Scandinavians Niklas Zennstrom and Janus Friis in Estonia, revolutionizing Internet communication by offering free voice calls between computers and affordable rates for calls to landlines and mobile phones. Over the years, and as Internet speeds improved, Skype evolved to
A: Were there any highlights at the Oscars this year? B: With 13 nods, French director Jacques Audiard’s “Emilia Perez” broke the record for most Oscar nominations earned by a non-English film. A: Wow, it broke the record of 10 Oscar nominations set by Taiwanese director Ang Lee’s “Crouching Tiger, Hidden Dragon.” B: On the eve of the Oscars, Lee was honored with the Lifetime Achievement Award at the Directors Guild of America (DGA) Awards. A: It seems that Hollywood has finally become more diverse. A: 今年的奧斯卡獎有什麼亮點嗎？ B: 法國導演賈克歐迪亞的《璀璨女人夢》榮獲13項提名，打破了非英語片紀錄！ A: 哇打破了台灣導演李安的《臥虎藏龍》10項提名紀錄。 B: 李安則在奧斯卡前夕，獲頒美國導演工會「終身成就獎」。 A: 看來好萊塢終於比較多元化啦。 (By Eddy Chang, Taipei Times／台北時報張迪)
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