金學堂英語的部落格

【LENS／聯合報／馮克芸譯】

It’s long been a mystery as to why we evolved to spend a third of our day in suspended animation, especially when predators lurked while we snoozed. Scientists are starting to understand the function of sleep, and why it’s important for adults and cranky teenagers.

Research at the University of Rochester’s medical school suggests that sleep gives our brains time to clear out all the detritus that has built up over a day of thinking, Maria Konnikova reported in The Times. Maiken Nedergaard, the Danish biologist leading the research, thinks there is a network of channels that clears out toxins with watery cerebrospinal fluid.

“We thought this cleaning process would require tremendous energy,” Dr. Nedergaard told The Times. “And so we asked, maybe this is something we do when we’re sleeping, when the brain is really not processing information.”

Her team discovered just that in studies they conducted on mice. When mice are sleeping or under anesthesia, their brains are cleaning out waste.

The problem is most of our brains are not getting enough cleaning time. Most adults should sleep seven to nine hours. But most Americans are getting one to two hours less sleep a night than they did 50 to 100 years ago and 38 minutes less on weeknights than 10 years ago. Some 50 to 70 million in the United States suffer from a sleep disorder.

The University of Pennsylvania’s Center for Sleep and Circadian Neurobiology has found that chronic sleep disruption damages neurons responsible for alertness and brain function, and a buildup of proteins linked to aging and neural degeneration.

“We’re really starting to realize that when we skip sleep, we may be doing irreparable damage to the brain,” Sigrid Veasey, who is leading the research, told The Times, “prematurely aging it or setting it up for heightened vulnerability to other insults.”

Researchers are finding links between insomnia and depression, which affects some 18 million Americans a year. Therapy to ease insomnia could double the effectiveness of depression treatment, scientists reported.

One way to improve sleep is to banish the gadgets from the bedroom, which is what the Times reporter Nick Bilton decided to do after he spent one too many nights checking his phone at 3 a.m.

Dr. David M. Claman, director of the Sleep Disorders Center at the University of California San Francisco Medical Center, told The Times that smartphones in the bedroom have led to a rise in sleep-related complaints.

“If you wake up in the middle of the night and check your phone, you will inevitably get frustrated and worried by something you’ve seen, leading your body to tense up,” Dr. Claman said.

Sleep is especially important for children and teenagers, who spend even more time in the sleep cycles that are responsible for strengthening neural connections and forming memories.

Less sleep is linked to more accidents, moodiness and aggression and, possibly, attention deficit disorders. It may increase the risk of drug use, sports injuries and lower academic performance.

Jessica Lahey wrote on The Times’s Motherlode blog that she thinks sleep is the most important factor for her children to do well in school. “Given the choice between one more review session for that French test and a bedtime that will ensure those nine hours, I will always encourage them to choose sleep.”

關於我們為何會進化成每天有三分之一的時間暫停活動，尤其是掠食者埋伏之際我們還會打盹小睡，長久以來，一直是個謎。科學家現在正開始了解睡眠的功能，以及睡眠對成人和躁動不安的青少年來說何以如此重要。

紐約時報記者瑪麗亞．柯尼科瓦報導，羅徹斯特大學醫學院的一項研究指出，睡眠給了我們一段時間，讓腦子能清除一天思考下來累積的渣滓。上述研究報告的主要作者、丹麥生物學家梅肯．尼德佳認為，人腦有一個由許多管道形成的網絡，會以水狀腦脊髓液來清除毒物。

尼德佳告訴紐時：「我們認為，這種清理程序需要極大的能量。因此我們想到，或許這就是我們睡覺、腦部並未處理資訊時所做的事。」

尼德佳的團隊在老鼠研究中發現腦部的清理程序，當老鼠睡覺時或被注射麻醉劑時，牠們的腦子就在清理廢物。

問題是，我們的腦子多半並未獲得足夠的清理時間。多數成年人每晚應該睡七到九小時，但如今多數美國人每晚比50到100年前的人少睡了一到二小時，而周一到周五的晚上比起10年前的人也少睡了38分鐘。全美約有5000萬到7000萬人有睡眠障礙。

賓州大學睡眠及全天神經生物學中心發現，長期睡眠崩解會破壞職司警覺性及腦部功能的神經細胞，而且會使與老化及神經退化有關的蛋白質增加累積。

領導上述研究的維西告訴紐時：「我們真的開始了解到，該睡不睡可能會對腦子造成無可挽回的傷害，讓腦子提早老化，或使腦子在面對其他傷害時更顯脆弱。」

研究人員現在發現，失眠與憂鬱息息相關，全美一年有1800萬人罹患憂鬱症。科學家說，治療失眠可讓憂鬱症的療效加倍。

改善睡眠的辦法之一，是把各種通聯上網機具趕出臥室，紐時記者比爾頓已決定身體力行，之前他經常凌晨三點還在查看手機。

舊金山加州大學醫學中心睡眠障礙中心主任克萊蒙博士告訴紐時，臥室裡的智慧型手機已使愈來愈多病患出現睡眠相關問題。

克萊蒙說：「如果你半夜醒來，查看手機，無可避免會覺得心煩意亂，且擔心你剛看到的東西，導致身體緊繃。」

對孩童及青少年來說，睡眠尤其重要，他們每天會花更多時間睡覺，睡眠可強化他們的神經連結及形成記憶。

睡得少可能更容易碰上意外、心情鬱卒、挑釁攻擊，或許還會有注意力缺乏障礙，也可能增加吸毒、運動傷害及成績低落的風險。

教育專家潔西卡．萊海在紐時親子部落格「媽媽藏」中撰文指出，要讓孩子在校表現良好，她認為最重要的因素就是睡眠。她說：「如果讓他們選擇：再做一回法語測驗復習或上床以睡足九小時，我一定會鼓勵他們選擇上床。」