晚上睡不着?起来学英语！
如果你是数亿外语学习者中的一员，睡得晚一点可能更有助于你学习——每天晚上睡前学外语，能记得更牢固。
Sleep has been known to have a positive impact on learning. A 2016 study investigated the effect that repeated practice and sleep have on the long-term retention of information, particularly foreign-language vocabulary. Over the course of two sessions done 12 hours apart, 40 participants practiced foreign-language vocabulary. Half of them learned in the morning and reviewed in the evening of the same day, while the other half learned in the evening, slept on it, and then reviewed that lesson the next morning. One week later (and again six months later), the researchers assessed the participants’ retention. They discovered that sleeping in between lessons led to much better long-term retention.
众所周知，眠有助于学习。一份2016年的研究调查了重复训练和睡眠对外语学习的影响。在两个人部分、共计12小时的实验中。40人分成两组学习外语单词。一组早上学习晚上复习，另一组晚上学习，再睡一觉，第二天早上复习。一周以后(第二次是六个月以后)，研究者测试了记忆效果，发现在中间睡过一觉的长期记忆效果更好。
This finding echoes the results of a recent analysis our team at Duolingo conducted on the learning habits of tens of thousands of language learners. However, we found that practicing before bed time isn’t the only trick: What’s key is making language learning a daily habit and sticking to it—consistently. Here’s the data that supports it.
这项调查结果和我们团队在多领国(Duolingo)上对一万人的学习习惯进行分析后的结果一致。但是，我们发现在睡前学习只是一个小技巧：真正的关键是让学习变成日常习惯，并持之以恒的坚持。调查过程如下：
The analysis
分析
First, we analyzed Duolingo users’ behavior to identify 14 groups based on their activity level at different times of day. (Activity level was measured by the number of Duolingo lessons each user completed during a given hour of the day on weekdays and weekends.) The following heat map illustrates the 14 usage groups. Red indicates a lot of activity, while blue indicates inactivity (and yellows or greens indicate moderate activity):
一开始，我们根据多领国用户一天不同时间段的活跃情况，将他们分成了14组(分工作日和周末两个部分)，如下图所示，颜色越红越活跃，越蓝越不活跃。
Each group has its own distinct preferences for when to spend time learning throughout the week. The “bed time” group, for example, is most active between 10pm and midnight on both weekdays (left) and weekends (right), as indicated by the dark red cells during those hours. Compare that with the “9-to-5” group, who uses Duolingo mostly during the working hours of 10am to 6pm on weekdays (left), but not much on weekends (right). These behavioral groups were all discovered automatically by a clustering algorithm, and then we gave names to each group based on the results.
每一组在学习时间的偏好上都不一样。例如，“睡觉时间(bed time)”这一组，就喜欢在晚上十点到午夜学习，不管是工作日还是周末。而“ 朝九晚五(9 to 5)”这一组，最喜欢在早上10点到下午六点之间学习，工作日是这样，但周末就不一定了。这些行为组都是归类算法自己发现的，我们只是按结果给他们取了一个名字。
Next, we analyzed Duolingo users’ performance using an additive factor model, which can estimate each user’s language ability while controlling for the inherent difficulty of each exercise (due to vocabulary, grammar, or other factors). We can use this model to assess and rank each Duolingo learner according to their proficiency level.
接着就是分析了，我们运用加性因子模型(additive factor model)评估了每一位学习者的效率等级。这种模型分析可以排除学习者的内在差异
When comparing Duolingo users’ proficiency across different groups, we found that those who practiced consistently just before bed time ranked higher than 52.9% of all users on average. This was the highest-performing group in our analysis.
对比不同小组的学习效率，我们发现，在睡前学习的小组提升达到52.9%，是我们分析的小组中最高的。
The best way to learn a language—and remember it
学语言的最佳办法
These results suggest a couple of things. Yes, those who study just before sleeping tend to perform better than other groups. But the time of day isn’t the only thing: Equally important is the fact that these language learners consistently studied daily before bed. Users in the “bed time” group made language practice a daily habit on weekdays and weekends alike. This wasn’t the case for several of the other lower-performing groups, such as the “weeknights,” “weekends,” or the “9-to-5” group that didn’t keep studying over the weekend.
这个结果说明两个问题。睡觉之前学习效果确实好。但时间选择不能解决一切问题，同样关键的还有学习者的坚持，睡前组的成员已经养成了习惯，无论是不是周末都坚持睡前学习。而其他组的成员则没有这个习惯。
Developing a regular daily habit is advantageous if you’re trying lead a healthier lifestyle, and language learning is no different. When people set aside focused time to learn and practice a skill, they appear to learn more than those who are less consistent—and perhaps just before bed turns out to be particularly good time to set aside, because you’re less likely to be interrupted by your workmate, laundry, or urge to sleep in.
培养日常习惯对形成健康的生活方式是有帮助的，学习也是一个道理。那些集中一个时间段学习的人，比那些没有计划的人学得更好，而且睡前这段时间确实很容易空出来，因为你不会被其他事情打扰。
While our analysis focused on users’ activity on Duolingo, language learning can take place in many forms. To go even further in making your practice a daily habit, try turning on French subtitles next time you’re watching your favorite TV show, or start listening to podcasts in Spanish on your daily commute. There are many ways to commit to making language learning part of your routine and, taken together, they can help you reach the level of proficiency you’re aiming for.
尽管我们的分析集中于多领国上的用户活跃，但语言学习也可以通过其他的方式。试试在日常生活中更进一步，下次看电视节目换成法语字幕，或者在通勤过程中听一听西班牙语播客。有很多办法都能让语言学习进入日常生活，而且他们确实能帮你更快达成你的目标。
As much as we might wish otherwise, there is no magic bullet for learning a language, but starting with dedicated practice every day—especially just before you sleep—goes a long way.
尽管我们都希望能又快又好，但学习语言确实没有捷径可以走，但从每天练习开始——从睡觉之前开始——确实能帮你学得好一点。
