But even if you don’t have depression, your circadian rhythm（生物鐘） may cause trouble. Most people’s natural cycle is somewhat longer than the 24-hour solar day, which means that, left to our own devices, we would get quickly get out of sync with（與...不一致） the external world. That is exactly what happens when humans are isolated from external cues — say, in a lab setting or stuck in a mine.
但即便你并未患上抑郁癥，你的生物鐘也可能造成麻煩。大部分人身體的天然周期比24小時的太陽日要長，這意味著如果讓身體自行其是，我們很快就會和外部世界不同步。當人類無法從外界獲得指引時，比如置身于實驗室環境中或被困在礦井里，情況恰恰如此。
本段包含詞匯
*even if 即使；雖然
*depression /d?’pre?n/ n.沮喪；蕭條
*somewhat /‘s?mw?t/ adv.稍微；有些；多少
*external /?k’st??nl/ adj.外來的；外部的；表面的
（形近詞：eternal 永恒的）
*isolate /‘a?s?le?t/ vt.使孤立；隔離
*be stuck in 困住；陷于...
The reason we don’t all walk around in a state of perpetual jet lag, waking and sleeping at random, is that our circadian rhythm evolved to be tied to the solar day. In other words, our internal clock is easily influenced and kept in check by the daylight cycle.
我們并不會長期處于倒不過時差的狀態、隨便醒來和入睡，是因為我們的生物鐘經過進化，與太陽日掛上了鉤。換句話說，我們的生物鐘很容易受日光周期影響和控制。
本段包含詞匯
*perpetual /p?’pet???l/ adj.永久的；永恒的；一再往復的
*at random 隨便地；任意地
*evolve /i’v?lv/ v.(使)逐步形成；進化
*solar /‘s??l?(r)/ adj.太陽的
*internal /?n’t??nl/ adj.國內的；內部的；身內的
I started thinking about this a few years ago, on a red-eye flight from New York to Rome, when I was rudely awakened somewhere over the Atlantic by the familiar airline ritual of opening the shades to blinding early-morning sunlight. What, I wondered, was this light doing to my brain?
我是在多年前乘坐一趟紅眼航班從紐約飛往羅馬時開始思考這個問題的。當時，我在大西洋上空的某個地方，被航班上為人熟知的慣例——打開百葉窗讓清晨刺眼的陽光照進來——猛然驚醒。我禁不住琢磨，這些光線對我的大腦有什么影響？
本段包含詞匯
*awaken /?’we?k?n/ v.意識到；喚醒
Atlantic /?t’l?nt?k/ n.大西洋
*wonder /‘w?nd?(r)/ v.驚奇；想知道；懷疑
