Learning is a physical process that involves strengthening certain connections among the brains neurons. That ability to change the brain varies according to the time of day； in particular， its enhanced during the day and more difficult at night. So how can you use time to your advantage？

學(xué)習(xí)是身體運(yùn)作的過程，該過程包括強(qiáng)化大腦神經(jīng)元之間的特定關(guān)聯(lián)。這種改變大腦的能力根據(jù)一天時(shí)間的變化有所不同。特別是白天學(xué)習(xí)能力會(huì)增強(qiáng)，晚上學(xué)習(xí)則更為吃力。那么，怎樣安排時(shí)間對(duì)你有利呢？

Ride the Wave

Every day， your body temperature starts low and rises slowly until late in the evening， when the wave crests1） and plunges down again for the night. Your internal temperature only varies by about a third of a degree， but thats enough to change the way your body—and， in particular， your brain—works. With more heat comes faster chemical reactions.

Thinking is a series of chemical exchanges， so calculation speed， memory formation and accuracy increase as the day goes on and peak with body temperature and heart rate—usually in the late afternoon. During the night and early hours of the morning， even if youre not sleep deprived， those powers decline.

Know Your Avian2） Type

Being a morning lark or a night owl is not a choice—youre born with it. Each of us has a chronotype3）， a tendency to get up early or stay up late， or perhaps flit4） somewhere in the middle. As much as you might force yourself into another schedule， your chronotype is largely genetic， and its affected by the length of your circadian cycle. A longer cycle leads to a later chronotype.

Age also plays a large role in a persons chronotype. While young children are early birds， adolescents begin to shift into a later phase. In the late teens and early 20s， we are the latest sleepers—and latest wakers—that we will ever be. After this peak comes a shift back to morningness. In fact， researchers proposed5） that whereas the end of puberty6） is defined as the time when your bones stop growing， the end of adolescence is the abrupt biological shift away from late sleeping that occurs around the age of 20.

Being a night owl means hitting your cognitive7） peak later in the day. Unfortunately， it also comes with real problems for students. Research shows that morning-active students have higher academic achievement and feel more immersed8） and focused in their studies， whereas night owls struggle with fatigue9） in the classroom. This problem disproportionately10） affects men and extroverts11）， who are more likely to be night owls. Not only is extroversion linked to evening chronotypes， it also tends to exacerbate12） the evening-active lifestyle because thats when much of our social activity goes on.

Study at a Fixed Time

One of the most powerful factors that influenced the evolution of human memory was the need to anticipate regular events—such as the appearance of food or predators13）—in the environment. Consequently， memory is closely linked to the internal clock， and when we learn things， there is an internal time stamp14） attached to those memories.

The brain can prepare for a bout15） of intensive focus if its required at the same time every day. A fixed-time learning session leads to better cognitive performance at that time of day， and if the task is demanding enough， your study sessions can even reset your body clock.

Keep a Sleeping Schedule

Decide on a bedtime and a time for waking up， then stick to it. Even on weekends， daily routines should remain roughly the same. Staying up much later on the weekend and sleeping in on Sunday—as many people do—leads to social jet lag16）. If you normally go to bed at 10：30 pm， but on Friday and Saturday you stay out until 1：30 am， its as if you have flown from your home in New York to Los Angeles for the weekend. Attention problems tend to follow during the week， even with a full eight hours of sleep every single night.

Nap Before Youre Tired

No matter how good your time-management skills， sometimes assignments pile up and deadlines converge17）， particularly towards the end of term. Few students get through their academic careers without pulling some late nights. A common approach is to power through18） the exhaustion at night， then nap the next day to recover. But naps are actually better at preventing fatigue than at helping you to recover from it. Napping during the day before a late night will boost your work and learning performance， even if you dont perceive the difference in yourself.

Take a Morning Walk

Before You Learn

Within the first half hour after waking， a flood of stress hormones—called the cortisol19） awakening response—surges20） through the body. This deluge21） catapults22） us out of the grogginess23） of sleep inertia24） and helps energize us for the day ahead， but it also impairs25） the formation of long-term memories. Anything thats important to remember should be saved for the second hour after waking.

Another obstacle to memory formation is the sleep hormone melatonin26）. A few minutes outside in the morning daylight will clear the melatonin out of the bloodstream and lend your brain the clarity it needs to start learning.

隨“波”而行

每一天，你的體溫一開始較低，隨后慢慢升高，在晚上到達(dá)峰值，繼而又在深夜驟降下來。雖然人的體溫變化幅度只有大約三分之一度，但這卻足以影響身體——尤其是大腦——的運(yùn)作。體溫越高，體內(nèi)的化學(xué)反應(yīng)就越快。

思考是一連串化學(xué)反應(yīng)的過程，因此，隨著一天時(shí)光的流逝，大腦的運(yùn)算速度、記憶能力和準(zhǔn)確度會(huì)不斷增強(qiáng)，并隨著體溫和心率的升高達(dá)到峰值——一般出現(xiàn)在近傍晚時(shí)。而在夜間和凌晨，就算你不缺覺，這些能力也會(huì)下降。

弄清自己是夜貓子還是早起鳥

你是早起鳥，還是夜貓子？這件事你無法左右，因?yàn)檫@是天生的。我們每個(gè)人都有一種作息模式，或習(xí)慣早起，或喜歡熬夜，或者也有可能處于中間狀態(tài)。你可能會(huì)盡力強(qiáng)迫自己換套作息時(shí)間，然而，你的作息模式多半是由基因決定的，受到自身生物鐘周期時(shí)長的影響。生物鐘周期越長，作息模式就會(huì)越晚。

年齡也對(duì)一個(gè)人的作息模式起到很大作用。孩童時(shí)期我們是早起鳥，但一進(jìn)入青春期就起得晚了。十八九歲到20歲出頭這個(gè)年齡段是我們一生當(dāng)中睡得最晚、起得最晚的時(shí)段。這個(gè)高峰一過，我們又變回早起型作息模式。事實(shí)上，研究人員就曾指出，骨骼停止生長時(shí)就可定義為發(fā)育期的結(jié)束，而青春期的結(jié)束則是以20歲左右晚睡的習(xí)慣突然生理性消失為標(biāo)志。

當(dāng)夜貓子意味著你會(huì)在當(dāng)天更晚的時(shí)段達(dá)到認(rèn)知水平的最高峰。不幸的是，對(duì)學(xué)生來說，這會(huì)帶來一些真正的問題。研究表明，早起的學(xué)生學(xué)習(xí)成績更好，更能專心致志、全神貫注地投入到學(xué)業(yè)中；而熬夜的學(xué)生則要在課堂上跟困倦做斗爭。這個(gè)問題更多地困擾著男性和性格外向者，因?yàn)樗麄兏锌赡艹蔀橐关堊?。性格外向的人不僅傾向于擁有晚睡型作息模式，而且這種在夜間活躍的生活方式往往還會(huì)變本加厲，因?yàn)槲覀兊纳缃换顒?dòng)大多是在晚上進(jìn)行。

在固定時(shí)間學(xué)習(xí)

人類需要對(duì)生存環(huán)境里經(jīng)常發(fā)生的事件——比如食物或天敵的出現(xiàn)——做出預(yù)測，這是影響人類記憶演化的最有力的因素之一。因此，人的記憶與生物鐘密切相關(guān)，在我們學(xué)習(xí)的時(shí)候，生物鐘就會(huì)為這些記憶做好相應(yīng)的時(shí)間標(biāo)記。

如果大腦需要每天都在同一時(shí)間運(yùn)轉(zhuǎn)，那么它就可以提前為這一高度專注的時(shí)段做好準(zhǔn)備。在固定時(shí)間段進(jìn)行學(xué)習(xí)可以增強(qiáng)當(dāng)天該段時(shí)間的認(rèn)知能力；如果學(xué)習(xí)任務(wù)特別繁重的話，你的學(xué)習(xí)時(shí)段甚至能夠重置你的生物鐘。

按時(shí)睡覺

定好睡覺和起床的時(shí)間，然后堅(jiān)持下去。即便是在周末，作息時(shí)間也應(yīng)該大體保持不變。很多人都在周末熬夜、在周日早上賴床，這樣會(huì)導(dǎo)致出現(xiàn)社會(huì)時(shí)差。如果你通常晚上10點(diǎn)半上床睡覺，但在周五和周六熬到1點(diǎn)半才睡，那就好比是從紐約的家中飛到洛杉磯過周末一樣。接下來的一周，即使你每晚都睡足八小時(shí)，也往往難以集中注意力。

不要等到累了才小睡

就算你再擅長時(shí)間管理，有時(shí)也會(huì)遇到作業(yè)扎堆、交作業(yè)期限趕在一起的情況，特別是在臨近期末的時(shí)候。很少有學(xué)生在上學(xué)期間沒有熬過那么幾晚。大家常見的做法是咬牙挺過疲乏的夜晚，然后在第二天小睡一會(huì)兒，便于恢復(fù)精力。然而，小睡其實(shí)更利于防止疲勞而不是幫你恢復(fù)精力。晚上熬夜之前，在白天小睡一會(huì)兒可以提高工作效率和學(xué)習(xí)效果，雖然你自己可能感覺不出差別。

早上學(xué)習(xí)之前散散步

清晨醒來最初的半小時(shí)里，我們的體內(nèi)會(huì)大量地涌出一種應(yīng)激激素，這種現(xiàn)象被稱為皮質(zhì)醇覺醒反應(yīng)。這一激素的大量涌來能使我們迅速擺脫睡意未消的迷糊狀態(tài)，提前為我們注入面對(duì)新一天的活力，但同時(shí)也會(huì)對(duì)長期記憶的形成造成干擾。因此，任何重要的、需要記憶的東西都應(yīng)該留到醒后的第二個(gè)小時(shí)再進(jìn)行記憶。

另一個(gè)阻礙記憶形成的因素是睡眠激素褪黑素。清晨在戶外活動(dòng)幾分鐘可以清除血液里的褪黑素，讓大腦變得清醒，從而利于展開學(xué)習(xí)。