If you've ever tried apartment living, you probably know the feeling. It's 11:30 at night, and the guy who lives above you has decided that this is the best time to schedule his Iron Maiden cover band practice. Or maybe you're the guy in the band, and you're sick and tired of the stuck-up dude downstairs stomping around and grinding coffee at the crack of dawn, when all decent headbangers are sleeping. Turns out that there's a very good reason both of these people hate each other, and it's all about the clocks hardwired into their genes.
现在是晚上11：30，住在你上面的人决定现在是安排他的铁娘子乐队练习的最佳时机。又或者你是乐队里的一员，你对楼下那个自以为是的家伙烦透了，他在黎明时分到处跺脚，磨咖啡，而所有体面的人都在睡觉。
Feel the Circadian Rhythm
In the world of sleep studies, there are "night owls" (people who are in bed after 11 p.m. and awake after 8 a.m.) and "larks" (the mythological creatures who get up before 8, even on the weekends). There are lots of studies about how the two different sleep schedules make for different brain types, but not a lot about what made them different in the first place. But according to a study published in Nature in 2016, a difference in circadian rhythms might be written into your genes.
在睡眠研究领域，分为“夜鹰”（指那些晚上11点以后睡早上8点以后醒的人）、和“百灵”（传说中每天早上8点以前起床，即使周末也不改变的生物）。关于这两种睡眠模式如何影响形成不同的大脑类型已经有了许多研究，但很少有关于为什么一开始就有两种睡眠模式的研究。不过，根据2016年《自然》杂志上发表的一片报告，生物钟节律很可能是刻在每个人的基因里的。
The study was a genome-wide association study (also known as a GWAS) using the DNA of nearly 90,000 people who had submitted their genetic material to 23andMe. The researchers discovered 15 genetic patterns that tended to be associated with being a lark. Some of those patterns lay close to patterns we know to determine circadian rhythms, and others lay near genes responsible for the eyes detecting light. The evidence is pretty clear: If you tend to wake up early, it's probably because your genes are telling you so.
这项研究是一项全基因组关联分析，使用的DNA来自近9万人提交给23andMe基因研究公司的基因样本。研究者们发现了15种趋向于使人成为百灵的基因片段，其中一些片段分布在离已经确定控制生物节律的基因片段附近，另外一些片段分布在控制眼睛感光的基因片段附近。证据很明显：如果你总是倾向于很早醒来，那很可能是你的基因在告诉你这么做。
A Swaying Pendulum
It's important to remember, however, that the circadian rhythm of an individual rarely stays static for that person's entire life. Besides your genes, there's a lot that determines exactly when you get sleepy and how much rest you need. Very broadly speaking, men tend to be night owls and women tend to be larks, and age plays a pretty major role in your rhythm as well. School-age kids lean towards lark-dom, while teenagers are notorious owls. Many adults transition back into larks as they grow older, but others will remain late-risers their entire life. In fact, there may be an evolutionary reason your bedtime drifts earlier as you age.
然而，需要注意的是，个体的生物钟节律几乎不会一生保持不变。除了基因的作用外，还有很多其它决定因素，一并影响着你什么时间入睡、需要睡多久。宽泛地讲，男人更趋向于夜鹰模式女人更趋向于百灵模式，另外年龄在节律的变化中也起着重要作用。学龄儿童倾向百灵状态，青少年是众人皆知的夜鹰模式，很多成年人随着年龄增大会重新转变成百灵模式，其余一些余生仍然会起床很晚。事实上，可能有某种进化的原因令你的入睡时间随着年龄增长而提前。
The jury is still out on if it's better to be up early or late (the TL;DR version is night owls are smarter but more depressed, and larks are happier but not necessarily healthier), but either way, you'll probably end up at both extremes at one point in your life.
早睡早起和晚睡哪个更好仍然在争论中（夜鹰们更聪明但也更压抑，百灵们更快乐但却未必更健康）。但无论如何，你可能最终会在自己人生某个阶段中处于两种极端。