Don't worry; we've all been there.

別擔心，我們都經歷過這種情況。

You're probably just stressed out.

你大概只是壓力太大。

Stress isn't always a bad thing.

壓力不總是一件壞事。

It can be handy for a burst of extra energy and focus, like when you're playing a competitive sport or have to speak in public.

當我們需要突發的能量或專注力時，壓力可能會派上用場，例如當你參與運動競賽或是必須公開演說時。

But when its continuous, the kind most of us face day in and day out, it actually begins to change your brain.

但是當壓力持續不斷，使得我們每天都必須面對時，它將開始改變大腦。

Chronic stress, like being overworked or having arguments at home, can affect brain size, its structure, and how it functions right down to the level of your genes.

如過度操勞或家庭爭吵等長期的壓力，會影響大腦的大小、結構和功能，甚至會影響基因。

Stress begins with something called the "hypothalamus pituitary adrenal axis", a series of interactions between endocrine glands in the brain and on the kidney, which controls your body's reaction to stress.

壓力源自於「下視丘-腦垂體-腎上腺軸」（簡稱 HPA軸），在大腦和腎中的內分泌腺一系列的相互作用後，會控制身體對壓力做出反應。

When your brain detects a stressful situation, your HPA axis is instantly activated and releases a hormone called "cortisol", which primes your body for instant action.

當大腦偵測到壓力狀態，HPA 軸會立即啟動並釋放「皮質醇」荷爾蒙，使身體準備好做出立即的反應。

But high levels of cortisol over long periods of time wreak havoc on your brain.

但是長期釋放高量的皮質醇會造成大腦的損害。

For example, chronic stress increases the activity level and number of neural connections in the amygdala, your brain's fear center.

例如，長期的壓力會增加活躍水平和大腦恐懼中心杏仁核中神經連接的數量。

And as levels of cortisol rise, electric signals in your hippocampus⏤the part of the brain associated with learning, memories, and stress control⏤deteriorate.

當皮質醇的水平上升，大腦中聯繫學習、記憶和控制壓力的部分——海馬迴裡面的電子訊號會惡化。

The hippocampus also inhibits the activity of the HPA axis, so when it weakens, so does your ability to control your stress.

海馬迴也會抑制 HPA 軸的活動，所以當它削弱時，你控制壓力的能力亦會下降。

That's not all, though.

不僅只是這樣。

Cortisol can literally cause your brain to shrink in size.

皮質醇會導致大腦的尺寸縮水。

Too much of it results in the loss of synaptic connections between neurons and the shrinking of your prefrontal cortex, the part of your brain that regulates behaviors like concentration, decision-making, judgment, and social interaction.

太多皮質醇會導致神經之間的突觸失去連接以及前額葉皮質縮小，前額葉皮質是大腦中調節行為的部分如專注力、決策力、判斷力及社交能力。

It also leads to fewer new brain cells being made in the hippocampus.

它也導致海馬迴中僅製造少數新的腦細胞。

This means chronic stress might make it harder for you to learn and remember things, and also set the stage for more serious mental problems, like depression and, eventually, Alzheimer's disease.

這意味著長期壓力可能對學習和記憶產生困難，也可能造成更嚴重的精神疾病，例如憂鬱症，最終導致阿茲海默症。

The effects of stress may filter right down to your brain's DNA.

壓力的影響可能直接滲透至大腦的 DNA。

An experiment showed that the amount of nurturing a mother rat provides its newborn baby plays a part in determining how that baby responds to stress later in life.

研究顯示，鼠媽媽提供新生幼兒的養育程度決定了幼鼠日後面對壓力的處理方式。

The pups of nurturing moms turned out less sensitive to stress because their brains developed more cortisol receptors, which stick to cortisol and dampen the stress response.

結果顯示，受鼠媽媽養育的幼鼠對壓力較不敏感，因為牠們的大腦發展出較多的皮質醇受體，受體與皮質醇作用並減緩對於壓力的反應。

The pups of negligent moms had the opposite outcome, and so, became more sensitive to stress throughout life.

至於那些不受鼠媽媽照顧的幼鼠有著節來不同的結果，牠們對生活中的壓力更加敏感。

These are considered "epigenetic changes", meaning that they affect which genes are expressed without directly changing the genetic code.

這被認為是表觀遺傳的改變，意思是它們影響的是沒有直接變更基因序列的基因。

And these changes can be reversed if the moms are swapped.

而且如果將鼠媽媽調換的話，這些改變是可以完全相反的。

But there's a surprising result.

但有一個驚人結果。

The epigenetic changes caused by one single mother rat were passed down to many generations of rats after her.

只由一隻鼠媽媽引起的表觀遺傳改變，會一代接著一代地傳下去。

In other words, the results of these actions were inheritable.

也就是說，結果證明基因是可以遺傳的。

It's not all bad news, though.

不過這不一定是壞消息。

There are many ways to reverse what cortisol does to your stressed brain.

有許多方法可以反轉皮質醇對充滿壓力的頭腦所做的事。

The most powerful weapons are exercise and meditation, which involves breathing deeply and being aware and focused on your surroundings.

最有效的方法為運動和靜坐，兩者都需要深呼吸並將注意力與專注力集中在周圍。

Both of these activities decrease your stress and increase the size of the hippocampus, thereby improving your memory.

這些活動會減少壓力，並增加海馬迴的大小，因而改善記憶力。

So, don't feel defeated by the pressures of daily life.

所以不要被日常生活中的壓力打敗。

Get in control of your stress before it takes control of you.

在被壓力控制前，你必須先控制它。