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)
Arriving on Aug. 2, US House of Representatives Speaker Nancy Pelosi shone out from the darkness in a pink pantsuit. Pelosi is famous for bringing her fashion A-game in punchy blazers and suits. Having a penchant for pops of color, the speaker often takes things a step further by coordinating her outfits from head to toe. Here are a few tips for building a chic wardrobe like Pelosi: Matching shoes to your outfit: Pelosi’s outfit tells us there are three guidelines for choosing the right shoes. You can either match your shoe color with your outfit, your tops underneath or simply
A: Hey, you’re watching “Extraordinary Attorney Woo.” Me too! B: Of course, it’s the biggest K-drama of the year and a global phenomenon. A: The lead actress Park Eun-bin plays a lawyer with autism. She plays the part so well that many viewers mistakenly believed the actress really is autistic. B: Then there’s lead actor Kang Tae-oh who plays the attorney’s handsome assistant. He’s totally my type! A: 原來你也在看《非常律師禹英禑》,我也是。 B: 當然啦,這可是今年全球最紅的韓劇呢。 A: 女主角朴恩斌飾演自閉症律師,演技好到讓觀眾以為她真的有自閉症。 B: 飾演她同事的男主角姜泰伍也好帥唷,完全是我的菜! (Translated by Edward Jones, Taipei Times/台北時報張聖恩)
A: I heard that the first episode of “Extraordinary Attorney Woo” achieved only 0.9 percent audience viewership. B: But by the 9th episode the audience share had reached 15.8 percent to become the most-viewed drama of the year. A: In addition to the gripping story, because the lawyer is a fan of whales, the drama features lots of whale animation. B: The scenes with the whale animation are really adorable. A: 聽說《非常律師》第一集,收視率只有0.9%。 B: 而到了第九集,收視率飆升到15.8%成為年度劇王。 A: 除了精彩的劇情,因為女主角是鯨魚迷,還有許多鯨魚的動畫特效。 B: 那些動畫鯨魚好可愛。 (Translated by Edward Jones, Taipei Times/台北時報張聖恩)
K-drama ‘Extraordinary Attorney’ causes sensation (3/3)《非常律師》成年度劇王(三) A: Is it actually possible for an autistic person to become an attorney? B: In Florida, US, there really is an autistic lawyer. A: “Extraordinary Attorney Woo” will have allowed many people to gain an insight into autism. B: I cannot wait for the big finale next week. A: 自閉症患者真的能擔任律師嗎? B: 在美國的佛羅里達州,真的有一位「自閉症律師」耶。 A: 藉由《非常律師》這部戲,也讓更多人認識了自閉症。 B: 我好期待下週播出的大結局喔。 (Translated by Edward Jones, Taipei Times/台北時報張聖恩)