Getting enough shut-eye is one of life’s biggest challenges. It’s recommended that the average person get at least 7 hours of sleep per night to stay healthy and alert, but is there a particular optimal time for going to bed?
獲得足夠的睡眠是人生最大的挑戰之一。有人建議稱我們每晚要至少睡7個小時才能保持健康和清醒，但是否有一個最佳睡覺時間呢？
The division of people into ’morning larks’ and ’night owls’ is based on our individual circadian rhythms - the internal body clock that keeps us going. A tiny region in the brain’s hypothalamus, called the suprachiasmatic nucleus (SCN), is the control centre of our internal timekeeping, and it runs in roughly 24-hour long cycles. Our sleep and wakefulness are regulated with hormones and neural activity from the SCN.
我們身體的內部生物鐘決定著我們每天的清醒與否，基於內部生物鐘所表現出的不同個人晝夜節律將人們劃分為“早晨百靈鳥”和“夜貓子”。大腦下丘腦中的一個小區域，稱為視交叉上核（SCN），是我們內部計時的控制中心，它以大約24小時的長週期運行。我們的睡眠和覺醒均是由視交叉上核的激素和神經活動調節。
The daily cycle of light and dark plays an important role in our circadian rhythms. "If you put a human into an environment without any light/dark signals or any other time cues, they will fall asleep approximately every 24 hours," writes sleep researcher Sally Ferguson from Central Queensland University in Australia. "Light is the strongest signal to our biological clock and is critical to [..] keeping us synchronised to the external environment."
光明和黑暗的日常循環在我們的晝夜節律中起著重要的作用。澳大利亞中央昆士蘭大學的睡眠研究人員薩利.弗格森寫道：“如果你把一個人置於一個沒有任何光/暗信號或任何其他時間暗示的環境中，他們大約每24小時就會睡著一次。”“光是我們生物鐘的最強信號，對於保持我們與外部環境同步至關重要。
So, should we all be going to bed at sundown and rising with the birds? Not necessarily, although exposure to light is closely linked to the production of melatonin, the hormone that makes us sleepy. When it’s light, the brain suppresses melatonin, which helps us stay alert. But people have individual differences in how soon after dark melatonin production kicks into gear, and this is why there is no set time for when a person starts getting sleepy.
那麼我們所有人都需要在日落時上床睡覺，鳥兒叫時起床嗎？這倒不是必須的，儘管暴露在光線中和使我們感到疲倦的激素—褪黑素的產生有密切關係，當有光線時，大腦抑制褪黑素的產生，從而保證我們清醒。但是人們在黑暗環境下褪黑素大量產生的快慢上存在差異，這也是為什麼對於每個人而言，沒有確定的時間開始犯困的原因。
It’s a mistake to go to bed too early, clinical sleep researcher Rafael Pelayo tells The Wall Street Journal. "Trying to go to sleep when your body wants to be awake is like swimming upstream."
“太早上床是錯誤的，”臨床的睡眠研究員Rafael Pelayo對《華爾街日報》表示。“在身體想要保持清醒的時候嘗試入睡就像逆流而上。”
In other words, if you’re fighting your natural rhythm, forcing yourself to go to bed early is only going to make you anxious about not being able to fall sleep. As insomnia researcher Allison Siebern from Stanford University in the US explains to Time magazine, the best time for a person to go to sleep is the hour when they feel the sleepiest. That’s easier said than done, though - particularly for people with inconsistent sleep schedules, such as shift workers.
換句話說，如果你與自己的自然規律作鬥爭，強迫自己很早地上床只會讓你為失眠而焦慮。就像來自美國的斯坦福大學的失眠研究員Allison Siebern對《時代週刊》解釋的那樣，一個人去睡覺的最好時間就是他最困的那個時間。不過這說的比做的容易——尤其是對那些睡覺時間不規律的人來說，比如按班輪換的工人。
Still, experts recommend that the best way to get a good night’s sleep is to try and rise around the same time every morning, and go to bed at our sleepiest, which might fluctuate slightly from day to day. To determine your optimal bedtime, set your alarm consistently, restrict the amount of time in bed to how many hours you normally need per night, and hit the sack 15 minutes before that. "Restricting your opportunity to sleep may actually make you go to bed later but the biologic drive to sleep will help you fall asleep faster and sleep deeper," explains Pelayo.
儘管如此，專家們建議，睡個好覺的最佳方法是每天早上嘗試在同一時間起床，並在我們最睏倦的時候上床睡覺，這可能每天都會略微波動。要確定最佳就寢時間，設置固定時間鬧鐘，將睡眠時間限制為每晚通常需要的時間，並提前15分鐘提示。 “限制你的睡眠機會實際上可能會讓你更晚上床睡覺，但生物規律驅動的睡眠將幫助你更快地入睡並睡得更深，”
One final note is a warning on sleep quality throughout the night. We sleep in roughly 90-minute cycles, shifting from deep sleep to lighter rapid eye movement (REM) sleep. The latter tends to occur more in the second half of the night, closer to daybreak - so if you often go to bed super-late, you may be getting more REM sleep, and less of the restorative deep stuff that makes you productive and alert.
最後一點是整晚睡眠質量的警告，我們睡眠的循環週期大概是90分鐘，從深度睡眠轉換到瞬間眼動睡眠。後者往往在臨近黎明的後半夜發生，所以如果你經常很晚上床睡覺，你得到更多的是瞬間眼動睡眠，這時我們不會得到高效和機敏的深層修復。
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