学习没效率？可能是生物钟在作祟

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？

学习是身体运作的过程，该过程包括强化大脑神经元之间的特定关联。这种改变大脑的能力根据一天时间的变化有所不同。特别是白天学习能力会增强，晚上学习则更为吃力。那么，怎样安排时间对你有利呢？

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.

随“波”而行

每一天，你的体温一开始较低，随后慢慢升高，在晚上到达峰值，继而又在深夜骤降下来。虽然人的体温变化幅度只有大约三分之一度，但这却足以影响身体——尤其是大脑——的运作。体温越高，体内的化学反应就越快。

思考是一连串化学反应的过程，因此，随着一天时光的流逝，大脑的运算速度、记忆能力和准确度会不断增强，并随着体温和心率的升高达到峰值——一般出现在近傍晚时。而在夜间和凌晨，就算你不缺觉，这些能力也会下降。

弄清自己是夜猫子还是早起鸟

你是早起鸟，还是夜猫子？这件事你无法左右，因为这是天生的。我们每个人都有一种作息模式，或习惯早起，或喜欢熬夜，或者也有可能处于中间状态。你可能会尽力强迫自己换套作息时间，然而，你的作息模式多半是由基因决定的，受到自身生物钟周期时长的影响。生物钟周期越长，作息模式就会越晚。

年龄也对一个人的作息模式起到很大作用。孩童时期我们是早起鸟，但一进入青春期就起得晚了。十八九岁到20岁出头这个年龄段是我们一生当中睡得最晚、起得最晚的时段。这个高峰一过，我们又变回早起型作息模式。事实上，研究人员就曾指出，骨骼停止生长时就可定义为发育期的结束，而青春期的结束则是以20岁左右晚睡的习惯突然生理性消失为标志。

当夜猫子意味着你会在当天更晚的时段达到认知水平的最高峰。不幸的是，对学生来说，这会带来一些真正的问题。研究表明，早起的学生学习成绩更好，更能专心致志、全神贯注地投入到学业中；而熬夜的学生则要在课堂上跟困倦做斗争。这个问题更多地困扰着男性和性格外向者，因为他们更有可能成为夜猫子。性格外向的人不仅倾向于拥有晚睡型作息模式，而且这种在夜间活跃的生活方式往往还会变本加厉，因为我们的社交活动大多是在晚上进行。

在固定时间学习

人类需要对生存环境里经常发生的事件——比如食物或天敌的出现——做出预测，这是影响人类记忆演化的最有力的因素之一。因此，人的记忆与生物钟密切相关，在我们学习的时候，生物钟就会为这些记忆做好相应的时间标记。

如果大脑需要每天都在同一时间运转，那么它就可以提前为这一高度专注的时段做好准备。在固定时间段进行学习可以增强当天该段时间的认知能力；如果学习任务特别繁重的话，你的学习时段甚至能够重置你的生物钟。

按时睡觉

定好睡觉和起床的时间，然后坚持下去。即便是在周末，作息时间也应该大体保持不变。很多人都在周末熬夜、在周日早上赖床，这样会导致出现社会时差。如果你通常晚上10点半上床睡觉，但在周五和周六熬到1点半才睡，那就好比是从纽约的家中飞到洛杉矶过周末一样。接下来的一周，即使你每晚都睡足八小时，也往往难以集中注意力。

不要等到累了才小睡

就算你再擅长时间管理，有时也会遇到作业扎堆、交作业期限赶在一起的情况，特别是在临近期末的时候。很少有学生在上学期间没有熬过那么几晚。大家常见的做法是咬牙挺过疲乏的夜晚，然后在第二天小睡一会儿，便于恢复精力。然而，小睡其实更利于防止疲劳而不是帮你恢复精力。晚上熬夜之前，在白天小睡一会儿可以提高工作效率和学习效果，虽然你自己可能感觉不出差别。

早上学习之前散散步

清晨醒来最初的半小时里，我们的体内会大量地涌出一种应激激素，这种现象被称为皮质醇觉醒反应。这一激素的大量涌来能使我们迅速摆脱睡意未消的迷糊状态，提前为我们注入面对新一天的活力，但同时也会对长期记忆的形成造成干扰。因此，任何重要的、需要记忆的东西都应该留到醒后的第二个小时再进行记忆。

另一个阻碍记忆形成的因素是睡眠激素褪黑素。清晨在户外活动几分钟可以清除血液里的褪黑素，让大脑变得清醒，从而利于展开学习。