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）
Despite anonymous accusations and attacks online, the Rising Star Rhythmic Gymnastics Association, founded last year by Ukraine-born Taiwanese entertainer Larisa Bakurova, has won acclaim internationally. On May 2, Bakurova announced that athletes from her association won one gold, one silver and two bronze medals at this year’s Gym Kids Eastern Cup. Bakurova, who is a former rhythmic gymnast, obtained her National ID Card to become a “new Taiwanese resident” in 2019. She said her association would continue to work hard, while expressing her appreciation for the public’s support while she faced the mud-slinging. Late last month, a netizen attacked her anonymously
Just get the landlord around to take a look at it (1/5) 請房東過來看就好了（一） B: You look like you could sleep for 1,000 years. A: Tell me about it. I’m exhausted. I’ve finally moved to the new apartment. Had I known it was going to be this much mental and physical effort… B: Well, it’s done now. You can sit back and relax in your new home. A: We still haven’t unpacked everything, the apartment looks like a bomb hit it, and we’re having a few teething problems. The whole thing is really testing my patience. B: You’re just tired. Your nerves are frayed. What kind of teething problems are you having? B: 你的樣子，看起來好像一躺下去就可以睡到天荒地老。 A:
Just get the landlord around to take a look at it (3/5) 請房東過來看就好了（三） A: We also have problems with the washing machine and the extractor fan in the bathroom. B: What’s wrong with the washing machine? A: We need to change the drain cover for the outlet pipe. The drain hole has bars going across it. I can’t get the pipe in, and if it isn’t a snug fit, it will flood the floor. B: And how about the extractor fan? What’s wrong with that? A: It doesn’t exist. A: 我們的洗衣機和浴室抽風機也有問題。 B: 洗衣機怎麼了？ A: 出水管用的排水孔，上面的蓋子必須換掉，因為排水孔的蓋子有金屬橫條，所以沒辦法把洗衣機排水管裝進去，如果沒有安裝密實，地板就會淹水。 B: 那抽風機是怎樣？是哪裡有問題？ A: 問題是沒有抽風機。 （Paul Cooper, Taipei Times／台北時報林俐凱譯） English 英文: Chinese 中文:
Just get the landlord around to take a look at it (4/5) 請房東過來看就好了（四） A: The third issue is that we wanted to put an oven in the kitchen. B: What’s stopping you? Isn’t there enough space for it? A: There’s plenty of space, but it needs a special cable. It runs on 220 volts, not 110 volts like most appliances. B: That’s just a small thing. Get in touch with the landlord and ask him to send an electrician around. If these are all the issues you’ve found with the new apartment, then you’re doing pretty well. A: I know, I know. There is one last problem, but it’s not really the
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