飯後犯困是因爲吃飽？真相震驚到了我！

Don't blame that long lunch meeting or low caffeine levels for your lack of care-factor in the early afternoon.
在下午的早些時候感覺身體被掏空，是怪午餐會議太長，還是體內咖啡因不夠。（它們表示這鍋我們不背）。

New research suggests your brain's reward functions are tuned in to your body's daily rhythms, with 2 pm being the low-point in your ability to feel good about nailing that big, important task.
最新研究表明，你的大腦可以根據你的日常規律自動調節來適應，到了下午兩點你的體能狀態會降到一個最低值，就不適合做什麼重大的任務啦。

The post-lunch slump is a familiar feeling for many people, often resulting in either a siesta or a masculine-sounding fizzy beverage.
很多人都會有午餐後怠倦的感覺，要麼就選擇小睡一會，要麼就來一個提神醒腦的氣泡飲料。

Researchers from Swinburne University of Technology in Australia decided to look into just how much of our desire to commit to a task was linked to our body's natural circadian rhythm.
來自澳大利亞的斯威本科技大學的研究人員想要了解，我們身體的晝夜節律對於完成任務有怎樣的影響。

Using an imaging technique called blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI), the team investigated how parts of the brain responded to a sense of reward at different times of the day in a group of 16 healthy, right-handed men.
使用一項醫學顯像技術血氧合度依賴性功能性磁共振成像，樣本人羣爲一組16人的右胚子，健康男性，來觀察他們的大腦對一天之內的對於獎勵刺激的反應。

The volunteers were given a task where they had to guess whether the hidden value of a digital card on a screen was higher or lower than five. Guessing correctly earned a reward, while an incorrect guess was penalised.
志願者需要完成在屏幕上猜電子牌的數是大於5還是小於5。猜對就得到獎勵，猜錯就會有相應的懲罰。

To motivate the volunteers, the researchers told them they would receive a bonus for the best of three trials conducted at three different times; 10 am, 2 pm, and 7 pm.
爲了鼓勵志願者，每日測試三次分別在10點，下午2點，晚上7點累計的前三名，還會得到額外的獎勵。

Watching their brains as they performed the task revealed a pattern of activity in a structure at the base of the brain called the putamen.
在他們完成任務的過程中，觀察他們大腦組織中“豆狀核”的活動模式。

This round blob of brain tissue manages a number of tasks, many revolving around learning and reinforcing behaviours that give the best chance of a good outcome. Having it primed at certain times over others can be interpreted as being ready to deal with an unexpected reward.
這種大腦組織中的圓形器官負責處理許多的任務，其中很多都是圍繞產生有益的學習和鞏固的行爲。它會讓實驗參與者認爲，只要比別人纔對次數多，而且達到一定數量，就意味着能夠得到額外的獎勵。

"We found that activations in the left putamen, the reward centre located at the base of the forebrain, were consistently lowest at the 2 pm measurement compared to the start and end of the day," says researcher Jamie Byrne.“
“我們發現活躍的區域位於左側“豆狀核”，獎勵反應的中心，在前腦的深處，連續幾天的測試比較發現，下午兩點的測試結果是一天三次中成績最差的。”研究人員傑米布萊恩說。

his is in line with their hypothesis, which claimed the brain's response to rewards varies according to the same biological rhythm that encourages us to wake, sleep, or feel hungry during the day.
這印證了他們之前假設，大腦對於獎勵刺激和身體讓我們醒來、睡覺、飢餓的生物節律是一樣的。

In other words, our brain isn't expecting a task to be as rewarding in the morning and late in the evening as it is in the middle of the day.
換句話說，比起早晨和晚上，在中午我們的大腦對於獎勵的渴望並沒有那麼強烈。

The research doesn't provide evidence explaining the reasons why our brains are primed to learn from experiences better at the beginning and end of a day. It was also only on a small group of males, so there's still plenty of room for debate.
研究並沒有說明爲什麼我們的大腦爲什麼早晚的學習能力強，而且式樣的樣本也只是一組爲數不多的男性，所以還有很多讓人質疑的空間。

It's possible that these are high-risk times, where our bodies are tired, hungry, or exposed to more threats.
說不定還有其他一些不好的原因，比如我們累了、餓了、感覺到危機四伏等等。

Having a brain that's primed to deal with problems that could result in unexpected rewards at certain times of day could save time and maximise benefits.
知道了大腦什麼時候最容易處理問題，就能夠在每天特定的時間基於額外的獎勵刺激，能夠節約時間，產生利潤的最大化。

For the rest of us, the research is a convenient excuse to take an extra hour to socialise in the lunch-room.
對於我們來說，這項研究給我們提供一個好的藉口，在用餐室盡情社交。

Just tell the boss your brain is expecting a better reward.
只要告訴你的老闆，你的大腦需要更好的獎勵刺激就行啦。