You know, the ability to "pitch a tent" in the morning, without any actual camping skills.

你知道，有能力"在早上搭帳篷"，沒有任何實際的露營技能。

Now that we got the one obligatory joke out of the way, we can get to the hard facts of nocturnal penile tumescence, otherwise known as "morning wood".

現在我們已經把一個強制性的笑話說出來了，我們可以開始討論夜間陰莖勃起的硬事實，也就是所謂的"晨木"。

It turns out morning erections are part of the normal sleep cycle and occur multiple times throughout the night.

原來晨勃是正常睡眠週期的一部分，整夜多次發生。

The mind and body go through stages of sleep, from non-REM stages, which gradually become deep sleep finally followed by REM or "Rapid Eye Movement" sleep which is actually fairly shallow sleep.

心靈和身體會經歷睡眠的階段，從非REM階段，逐漸變成深層睡眠最後是REM或"快速眼動"睡眠，其實是相當淺的睡眠。

This cycle occurs between 4 or 5 times a night.

這個週期每晚發生4到5次。

As you enter REM sleep, not only do dreams occur, but a few physiological changes take place as well.

當你進入REM睡眠時，不僅會做夢，還會發生一些生理變化。

Namely, your brain begins to shut off some neurotransmitters in an effort to regulate your body, and in some cases stop you from acting out your dreams.

也就是說，你的大腦開始關閉一些神經遞質，以努力調節你的身體，在某些情況下，你會阻止你的夢想行動。

One of these neurotranmitters, norepinephrine, happens to be involved with the control of erections.

這些神經遞質之一，去甲腎上腺素，恰好與勃起的控制有關。

Specifically it causes vasoconstriction of penis blood vessels, actively preventing an erection.

具體來說就是導致陰莖血管收縮，主動阻止勃起。

It is like a stop sign for blood flow. But as you enter REM sleep, norepinephrine decreases and testosterone related actions are now able to take place.

它就像一個血流的停止信號。 但當你進入REM睡眠時，去甲腎上腺素減少，睪丸激素相關的動作就能夠發生了。

This leads to vasodilation, or increased blood flow to the blood vessels, ultimately causing an erection.

這就會導致血管擴張，或增加血管的血流量，最終導致勃起。

Why is this important?

為什麼這很重要？

Well, similar to muscle and other tissue, at night this extra blood increases oxygenation, serving as a system of repair and helping to maintain functionality.

嗯，與肌肉和其他組織類似，在夜間，這些額外的血液會增加氧氣，作為一個修復系統，幫助維持功能。

But why do we often wake up to this pleasant surprise?

但為什麼我們常常在這種愉悅的驚喜中醒來？

Well, we often wake up just out of REM sleep, and as a result see the remnants of this sleep stage.

好吧，我們經常是剛從REM睡眠中醒來，結果就看到了這個睡眠階段的遺蹟。

There is also evidence that a full bladder can contribute to morning wood.

也有證據表明，膀胱充盈會導致晨木。

The increased baldder size for the night stimulates a region of the spinal cord which can cause a reflex erection.

大年夜量的球囊增大年夜刺激了脊髓的一個區域，可引起反射性勃起。

The physiological benefit of this is to prevent you from urinating in your sleep.

生理上的好處是防止你在睡眠中排尿。

But most men can attest to the difficulty proposed by this conundrum after waking in the morning.

但大多數男人都能證明早上醒來後這個難題提出的困難。

Rise and shine.

興起，閃閃發光。

Got a burning questions you want answered? Ask it in the comments or on facebook and twitter.

你有一個迫切的問題想得到解答嗎？請在評論中或在facebook和twitter上提問。

Or subscribe for more weekly science videos.

或訂閱更多每週科學視頻。