科学解答什么时间上床睡觉最合适！不用强迫自己早睡了……
Getting enough shut-eye is one of life’s biggest challenges.
获得足够的睡眠是人生最大的挑战之一。
It’s recommended that the average person get at least 7 hours of sleep per night to stay healthy and alert, but is there a particular optimal time for going to bed?
有人建议称我们每晚要至少睡7个小时才能保持健康和清醒，但是否有一个最佳睡觉时间呢？
The division of people into ’morning larks’ and ’night owls’ is based on our individual circadian rhythms - the internal body clock that keeps us going.
我们身体的内部生物钟决定着我们每天的清醒与否，基于内部生物钟所表现出的不同个人昼夜节律将人们划分为“早晨百灵鸟”和“夜猫子”。
A tiny region in the brain’s hypothalamus, called the suprachiasmatic nucleus (SCN), is the control centre of our internal timekeeping, and it runs in roughly 24-hour long cycles. Our sleep and wakefulness are regulated with hormones and neural activity from the SCN.
大脑下丘脑中的一个小区域，称为视交叉上核（SCN），是我们内部计时的控制中心，它以大约24小时的长周期运行。我们的睡眠和觉醒均是由视交叉上核的激素和神经活动调节。
The daily cycle of light and dark plays an important role in our circadian rhythms.
光明和黑暗的日常循环在我们的昼夜节律中起着重要的作用。
"If you put a human into an environment without any light/dark signals or any other time cues, they will fall asleep approximately every 24 hours," writes sleep researcher Sally Ferguson from Central Queensland University in Australia.
澳大利亚中央昆士兰大学的睡眠研究人员萨利.弗格森写道：“如果你把一个人置于一个没有任何光/暗信号或任何其他时间暗示的环境中，他们大约每24小时就会睡着一次。”
"Light is the strongest signal to our biological clock and is critical to keeping us synchronised to the external environment."
“光是我们生物钟的最强信号，对于保持我们与外部环境同步至关重要。
So, should we all be going to bed at sundown and rising with the birds? Not necessarily, although exposure to light is closely linked to the production of melatonin, the hormone that makes us sleepy.
那么我们所有人都需要在日落时上床睡觉，鸟儿叫时起床吗？这倒不是必须的，尽管暴露在光线中和使我们感到疲倦的激素—褪黑素的产生有密切关系。
When it’s light, the brain suppresses melatonin, which helps us stay alert. But people have individual differences in how soon after dark melatonin production kicks into gear, and this is why there is no set time for when a person starts getting sleepy.
当有光线时，大脑抑制褪黑素的产生，从而保证我们清醒。但是人们在黑暗环境下褪黑素大量产生的快慢上存在差异，这也是为什么对于每个人而言，没有确定的时间开始犯困的原因。
It’s a mistake to go to bed too early, clinical sleep researcher Rafael Pelayo tells The Wall Street Journal. "Trying to go to sleep when your body wants to be awake is like swimming upstream."
“太早上床是错误的，”临床的睡眠研究员Rafael Pelayo对《华尔街日报》表示。“在身体想要保持清醒的时候尝试入睡就像逆流而上。”
In other words, if you’re fighting your natural rhythm, forcing yourself to go to bed early is only going to make you anxious about not being able to fall sleep.
换句话说，如果你与自己的自然规律作斗争，强迫自己很早地上床只会让你为失眠而焦虑。
As insomnia researcher Allison Siebern from Stanford University in the US explains to Time magazine, the best time for a person to go to sleep is the hour when they feel the sleepiest.
就像来自美国的斯坦福大学的失眠研究员Allison Siebern对《时代周刊》解释的那样，一个人去睡觉的最好时间就是他最困的那个时间。
That’s easier said than done, though - particularly for people with inconsistent sleep schedules, such as shift workers.
不过这说的比做的容易——尤其是对那些睡觉时间不规律的人来说，比如按班轮换的工人。
Still, experts recommend that the best way to get a good night’s sleep is to try and rise around the same time every morning, and go to bed at our sleepiest, which might fluctuate slightly from day to day.
尽管如此，专家们建议，睡个好觉的最佳方法是每天早上尝试在同一时间起床，并在我们最困倦的时候上床睡觉，这可能每天都会略微波动。
To determine your optimal bedtime, set your alarm consistently, restrict the amount of time in bed to how many hours you normally need per night, and hit the sack 15 minutes before that.
要确定最佳就寝时间，设置固定时间闹钟，将睡眠时间限制为每晚通常需要的时间，并提前15分钟提示。
"Restricting your opportunity to sleep may actually make you go to bed later but the biologic drive to sleep will help you fall asleep faster and sleep deeper," explains Pelayo.
“限制你的睡眠机会实际上可能会让你更晚上床睡觉，但生物规律驱动的睡眠将帮助你更快地入睡并睡得更深，”
One final note is a warning on sleep quality throughout the night. We sleep in roughly 90-minute cycles, shifting from deep sleep to lighter rapid eye movement (REM) sleep.
最后一点是整晚睡眠质量的警告，我们睡眠的循环周期大概是90分钟，从深度睡眠转换到瞬间眼动睡眠。
The latter tends to occur more in the second half of the night, closer to daybreak - so if you often go to bed super-late, you may be getting more REM sleep, and less of the restorative deep stuff that makes you productive and alert.
后者往往在临近黎明的后半夜发生，所以如果你经常很晚上床睡觉，你得到更多的是瞬间眼动睡眠，这时我们不会得到高效和机敏的深层修复。TED演讲课
英文来源：Science alert、心理分析家