關於生物鐘的十大真相(上)

Remember that scene in "My Cousin Vinny" where Marisa Tomei says, "My biological clock is ticking likes this" and she starts stomping hard on the floor? When someone says that a woman's biological clock is ticking, it usually means that she actively wants to have a baby and feels time may be short. Scientists debate whether this is a real physiological response from the body as fertility decreases or if it's all in the head. While men can feel a biological clock ticking too, it's generally not with the same urgency, as their time to father a child is much longer than a woman's is to have one. At least, that was conventional wisdom. As both men and women are becoming parents at older ages, scientists have discovered that the father's age may have More to do with a child's genetic health than that of his or her mom. That's just one use of the term "biological clock." Turns out that every living thing – men, women, animals, plants, insects, and algae – all have internal "body clocks" determined by a variety of biological rhythms. These physical, mental and behavioral patterns follow a predictable cycle every day, one that is determined largely by the body's response to light and dark. So why do we have these clocks, and what do they do for us? Here are 10 facts that may surprise you.

大家還記得電影《我的堂兄文尼》中的一個場景嗎？瑪麗莎·託梅說：“我的生物鐘正在滴答作響！”然後她開始在地板上瘋狂地跺腳。當有人提到一個女性的生物鐘正在滴答作響，那通常意味着她很渴望生一個孩子而且感到時間實在是太緊迫了。科學家們就這一生物鐘是否是因生育能力下降而導致的真實生理反應，亦或是純粹的心理作用而爭論不休。不過男人也可以體會到生物鐘滴答作響的感覺，但它通常並不像女人的生物鐘那樣讓人倍感緊迫，因爲他們當爹的時間比女人生娃的時間長多了。但不管怎樣，這都是一種傳統的說法。隨着年齡的不斷增大，男人和女人終會爲人父母，科學家們發現，父親的年齡對孩子基因健康的影響要比母親大。這僅僅只是“生物鐘”的作用之一。結果表明，每一個生物——男人、女人、動物、植物、昆蟲、藻類——它們的身體內部都有一個生物鐘——由不同的生物節律決定。這些生理、心理和行爲模式絕大部分取決於身體對光線強弱做出的不同反應，每天在可預測的週期內循環。所以我們爲什麼會擁有生物鐘？它們能爲我們做什麼？下面10個事實大概會讓你震驚。

's a Complex Clock

10.生物鐘很複雜

The body clock isn't some rinky-dink Mickey Mouse watch. In fact, it's a series of clocks controlled by a single "master clock" located in the brain. The system works like this: Genes within the body include instructions for making proteins, which are produced in waves that rise and fall over the course of a day in a type of 24-hour cycle.

生物鐘絕對不是一塊破舊的普通米老鼠手錶。事實上，它是一系列由大腦的“主時鐘”控制的時鐘。生物鐘系統是這樣運作的：身體內的基因，包括那些合成蛋白質的指令都是在一天24小時循環的人體波動中形成的。

The master clock manages these circadian rhythms using a group of roughly 20,000 nerve cells called the suprachiasmatic nuclei (SCN), located in the hypothalamus. This section of the brain sits above the optic nerve and produces the hormones that govern body temperature, hunger, sex drive and other workings of the body. The patterns created not only dictate when we eat and sleep, but also control heart rate and the production of blood cells and blood sugar. Although the genes and proteins generally determine individual rhythms, outside factors related to light and dark can also have a significant impact on how your body "tells time".

主時鐘調節這些晝夜節律需使用大約20000個位於下丘腦的神經細胞——視交叉上核。下丘腦位於視神經之上,其產生的荷爾蒙能控制體溫、攝食、性慾和身體的其他性能。它不僅指示我們何時吃飯睡覺，還控制心率以及生產血細胞和血糖。一般來說，基因和蛋白質決定個人生物節律,但例如光線強弱等的外在因素也可以對你身體的報時產生較大影響。

tonin Is Our Body's Sleep Aid

9.褪黑素有助於人體睡眠

Among the many hormones pumped through the body, the suprachiasmatic nuclei (SCN) controls the production of the one that makes people want to curl up in a ball on the nearest couch and catch a few zzzs. Melatonin is a naturally occurring chemical that helps regulate the circadian rhythm. The more of it that the body produces, the more likely you are to get sleepy.

在人體內的各種激素裏，視交叉上核控制的激素可以讓人們想要趕緊找個沙發躺下呼呼大睡。褪黑素是一種天然的化學物質,可以幫助人體調節晝夜節律。身體內產生的褪黑素越多，你就越有可能會昏昏欲睡。

Your melatonin production schedule varies based on light. Remember that the SCN is located just above the optic nerve, which sends information from the eyes to the brain. The less light that comes in – after the sun goes down and the sky becomes dark, for example – the more melatonin the SCN tells the brain to make. Some folks who suffer from sleep disorders will pop melatonin pills to help them get some rest. The effect of these supplements, which are available without a prescription and not regulated in the same way as pharmaceutical drugs, is still not clear. Experts warn that users should be careful to monitor the size and timing of doses so as not to throw off their natural body clocks.

褪黑素利用光來校準生產時間表。記住，視交叉上核只存在視覺神經上方，通過眼睛把信息傳遞到大腦。舉個例子，當太陽下山、天空也暗下來後——進入眼睛的光線變得越來越少，視交叉上核就會提醒大腦生產更多的褪黑素。有些患有睡眠障礙的人會使用褪黑素藥物來助眠。但這些無需處方也並不像普通藥品一樣接受監管的激素到底會對人體產生什麼影響還是未知數。專家警告說，藥物使用者應仔細監測劑量的大小和服用時間，以免打破人體的自然生物鐘。

Body Clock Adapts to Location Changes

8.生物鐘會根據位置改變自我調節

Think about the body clock as a human version of the one on your smartphone. If you turn off the phone when you board a plane in New York and turn it back on when your flight lands in Los Angeles, you will notice that the clock automatically adjusts the time to reflect that you're now in a different zone. In the same way, your body clock will eventually adjust to the new light/dark cycle on the West Coast.

把你的生物鐘想作是智能手機裏的另一個人類版本。假如你在紐約登機時關閉手機，然後在舊金山降落時再打開手機，你會注意到，手機的時間已隨時區變化自動調節並且提示你已身處在不同的時區。同樣地，你的生物鐘最終也會適應西海岸的晝夜。

Anyone who's ever suffered from jet lag knows that the shift doesn't happen right away. Your body has been trained to release melatonin at a certain time each night, and will initially continue to do so even when the optic nerve tells the brain that it's still light outside. Eventually however, and your brain will time the melatonin release to the darkness. In other words, the clock slowly rewinds itself to reflect the rising and falling of the sun and to ensure that you don't spend all of the prime California beach time snoring in your hotel room.

任何曾經有過時差反應的人都知道，生物鐘的轉變是不會立馬發生的，因爲只有在晚上的某一特定時間，你的身體纔會分泌褪黑素。所以在適應期內，即使視覺神經傳遞給大腦“現在是白天”的信息，你的身體還是會在原定時間內分泌褪黑素。在生物鐘完全適應了新時區的時間後，你的大腦纔會在夜間傳達“分泌褪黑素”的信息。也就是說，你的生物鐘會自我調整，以適應新時區的晝夜，確保你在加州海灘度假時，不至於所有的時間都在酒店房間裏呼呼大睡。

It Doesn't Adapt to Daylight Saving Time

7.但生物鐘無法適應夏令時

Most American, Canadian and European timepieces spring forward every March, when the powers that be move the official time up an hour so as to allow people to make the most of daylight. Thought to be originally cooked up by Benjamin Franklin, daylight saving time took hold during World War I and became the law of (most) of the land in the U.S. in 1966. Then-President Lyndon Johnson signed legislation requiring official timekeepers to move their clocks forward an hour each spring and back an hour every fall.

美國、加拿大和歐洲的大多數計時器每年從三月起實行夏令時，政府把官方時間提前一小時，以便人們充分享受日光。夏令時由本傑明·富蘭克林提出，在一戰期間正式執行。1966年，美國絕大部分地區通過立法，確定使用夏令時。當時的總統林登·約翰遜簽署了此項法案，要求官方計時員在每年春季開始時調前一小時，每年秋季結束時調後一小時。

The problem is that no one seems to have consulted our body clocks before agreeing to this twice-a-year adjustment. Moving the time ahead an hour does a number on circadian rhythms, particularly in the days immediately after the change when the sun still comes up around the same time. If your alarm goes off at 7 a.m. the day after it springs forward, your body still thinks it's 6 a.m. Because the sun rises later in small increments, it's probably still dark out, and will remain dark for a few months. That means that your body won't shut off the melatonin faucet just yet. One study showed that people's circadian rhythms never fully adjust to daylight saving time and sleep behavior only returns to normal when we go back to regular time.

問題是，在同意一年兩次的調整前，並沒有人考慮過我們的生物鐘能否適應夏令時。把時間提前一小時破壞了晝夜節律，尤其是在更改後幾天，太陽依舊在相同的時間升起。在夏令時開始後，如果你的鬧鐘顯示的是7：00am，你的身體依然會默認爲是6：00am。因爲太陽升起得比較慢，外面可能還是一片黑暗，這種情況可能還會持續幾個月。那就意味着在此期間，你的身體並不會停止分泌褪黑素。一項研究發現，人們的生理節律無法完全適應夏令時，而且只有當人們回到正常時間，其睡眠習慣纔會迴歸正常。

s Do It, Bears Do It

6.萬物皆有生物鐘

It's like the music group Bloodhound Gang says: "You and me, baby, ain't nothing but mammals." Other mammals also have rhythm-based body clocks that dictate when they rise in the morning and when they lie down for some shut-eye at night. In fact, bears depend on seasonal circadian rhythms to tell them when to hibernate for the winter and when to come out from their hiding places. Birds similarly fly south for the winter based on circadian (or circannual) rhythms that adapt to changes in temperature and the decreasing amount of sunlight per day.

正如血性獵犬幫搖滾樂合唱團唱的那樣，“你和我，寶貝，只是哺乳動物而已”。而其他哺乳動物的作息也是依賴於這種有規律的生物鐘，早上何時甦醒，晚上又何時入眠。事實上熊也依賴於季節性的晝夜節律，根據時令選擇什麼時候該去冬眠了，什麼時候又該從藏身的地方出來。類似地，鳥類向南方遷徙也是爲了適應冬季每日溫度下降、光照減少的晝夜節律。

It isn't just mammals who keep time naturally either. Internal rhythms drive plants to open their leaves at dawn and close them at night. They also determine when flowers bloom seasonally.

並不是只有哺乳動物纔會有規律的作息時間，植物的內部生物鐘會促使它們在黎明的時候舒展開葉子，在傍晚的時候閉合。此外，這種內部生物鐘也會決定季節性開花的時間。

審校：圍巾、煙囪 編輯：listen 來源：前十網