The early bird rises with the sun, springing out of bed abuzz with energy.

這裡有一隻早起的鳥 和一隻夜行貓頭鷹，

As the day goes on, they slowly get more and more exhausted

都待在牠們的天然棲息地中。

until finally crashing around sunset.

早起的鳥和太陽一起起來， 活力滿滿地跳下床。

Meanwhile, the night owl rises long after the sun,

隨著一天進展， 他們慢慢地耗盡了精力，

stumbling groggily from their bed.

終於在日落時倒下。

After about 30 minutes— or a cup of coffee—

同時，夜行貓頭鷹起來的 時間遠比太陽晚很多，

they begin to come to life.

且是迷迷糊糊地從床上爬起來。

But they don't really hit their stride until later in the day,

大約三十分鐘後── 或一杯咖啡後──

at which point they comfortably coast past sunset,

他們才活起來。

only heading to bed in the early hours of the morning.

但他們要到一天的晚些時候才會 開始找到節奏展現效率，

For many, this is a familiar story, and one that's easy to cast yourself in.

此時，他們進入狀況， 在日落後仍能舒適地繼續做事，

But how many people are truly night owls or early birds?

要到清晨時才上床去。

And are our natural sleep schedules predetermined at birth,

對許多人而言，這個故事很熟悉，

or can we change them?

且很容易對號入座。

The truth is there's a lot of space between these extremes,

但有哪些人真的是夜貓子或早起鳥？

and most people fall somewhere in the middle.

在出生時我們的自然睡眠時程表 就已經被預先決定了嗎？

These behaviors are determined by our circadian system—

或者我們可以改變它？

which is anchored by a pair of nerve cell clusters

事實是，在這兩極端中間 還有許多空間，

located in the anterior hypothalamus.

且大部分人都落在這中間區域。

These nerve cells respond to light exposure coming in through your eyes

我們的生理時鐘系統 會決定這些行為──

to track the day-night cycle that dictates your body's internal clock,

視丘的一對神經細胞叢 會決定生理時鐘。

or circadian rhythm.

這些神經細胞接觸到 透過你眼睛進入的光之後，

That steady rhythm helps determine the body's flow of hormones,

會追蹤日夜循環，而這個循環 會支配你體內的時鐘，

with the broader circadian system acting like a conductor

或稱二十四小時生理節奏。

that keeps your organs functioning in time with one another.

這個穩定的節奏能協助 決定體內荷爾蒙的流動，

And a major part of that performance is managing the body's transitions

更廣泛的生理節奏系統 扮演的角色就像是指揮家，

between being awake and being asleep.

持續協調你的器官，讓它們能同時運作。

Now, your circadian system can't just decide its bedtime and knock you out.

而指揮家所指揮的演出， 重點之一在於管理身體

However, by tracking how much light you typically get

在清醒和睡眠之間的轉換。

and when in your waking hours you usually get it,

你的二十四小時生理系統不能 單純決定睡覺時間然後把你打昏。

the system can make predictions about when you're likely to need sleep

然而，靠著追蹤你通常接收多少光量

and prepare your body accordingly.

以及你通常在哪些 清醒時段接收到光，

For example, if you consistently go to sleep around 10 pm,

這個系統就能預測 你何時可能會需要睡覺，

your circadian system will start producing sleep-inducing melatonin

並依此預測來幫你的身體做好準備。

around two hours before then to tell your body it's time for bed.

比如，如果你經常 在大約晚上十點上床睡覺，

So if this rhythm is molded by our sleep habits,

你的二十四小時生理系統 在大約兩小時前就會開始

can we change it just by sticking to a strict schedule?

產生催眠褪黑激素，告訴 你的身體該是上床的時候了。

To a degree.

若這種節奏是由我們的 睡眠習慣所形塑出來的，

Everyone's bodies are unique,

我們能否靠著堅持遵守 嚴格的時程表來改變它呢？

so even two people with the same sleep schedule might have different experiences

某種程度上可以。 每個人的身體都是獨特的。

based on their circadian system's hormonal quirks.

即使兩個人的睡眠時程表都一樣，

For example, where early birds generally flood with cortisol just before waking up,

也可能因為荷爾蒙特性 差別而有不同的體驗。

night owls often have their cortisol peak roughly 30 minutes after getting up.

比如，早起鳥通常在醒來之前 就會充滿可體松，

Hormonal differences like these determine how you experience your circadian rhythm.

夜貓子的可體松達到高峰的時間 通常是起床後三十分鐘左右，

And while these factors can shift with age,

像這樣的荷爾蒙差異會決定你對 你二十四小時生理節奏的體驗。

you're unlikely to grow out of your body's preferred sleep schedule.

雖然這些因子可能會隨年齡轉變，

That said, you can cultivate habits to help or hinder your circadian rhythm.

你仍然不太可能可以改變 你身體偏好的睡眠時程表。

Keeping consistent sleeping hours helps your body accurately predict

儘管如此，你依然可以培養習慣 來協助或阻礙你的生理節奏。

when to send out hormones,

維持一致的睡眠時段 能協助你的身體正確預測

making it easier to stick to your schedule.

何時要發出荷爾蒙，

Conversely, research in sleep deprived college students

讓遵守你的時程表變得更容易。

has found their unpredictable sleeping habits

相反的，針對睡眠不足的 大學生所做的研究

weaken their entire circadian system.

發現他們不固定的睡眠習慣

Compromised circadian rhythms are less effective

會削弱他們整個 二十四小時生理系統。

at coordinating organ functioning and can incur health risks

受損害的生理節奏 比較沒辬法那麼有效率地

like metabolic disorders and vulnerable immune systems.

協調器官功能， 可能會造成健康風險，

But perhaps just as important as sleep hygiene is light hygiene.

比如心陳代謝疾病 和免疫系統變脆弱。

Getting sufficient contrast between bright daylight and dimmer nighttime light

但也許，光線衛生 和睡眠衛生同等重要。

is essential for synchronizing your circadian rhythm,

明亮的日光和暗淡的夜晚光線 之間要有足夠的對比，

and nothing establishes this contrast better than sunlight.

這點對於你的生理節奏 同步化是很重要的，

Even on overcast days, sunlight is much brighter than standard indoor lighting.

而最能夠建立這種 對比的就是太陽光。

So if you're typically awake during the day,

即使是多雲的日子，太陽光 也還是比標準的室內光線還更亮。

try getting outside as soon as possible to teach your body

所以如果你在白天通常都是醒著的，

when to be active and alert.

試著盡可能到室外去，教導你的身體

It's difficult to maintain a sleep schedule

何時要活動及警覺。

that pushes against your body's preferences.

維持遵守和你身體偏好 抵觸的睡眠時程表並不容易，

And even if you succeed for months,

即使你成功做到幾個月，

it only takes one bad night to send your circadian system back to baseline.

只要一個晚上失守，就能讓你的 二十四小時生理系統回到原點。

But whether you're an early bird, night owl, or somewhere in between,

但，不論你是早起鳥、夜貓子， 或兩者之間的某一種，

it's important to remember that as long as you're consistent,

很重要的是要記得，只要你貫徹，

there's no wrong time to wake up or go to sleep.

沒有什麼錯的起床時間或上床時間。

What matters most is getting enough rest for the day ahead.

最重要是要為接下來的 一天取得足夠的休息。