Other people say that REM sleep is the only essential phase of sleep, so core sleep isn't necessary.

所以相对来讲，是否保证核心睡眠是没有必要的。

youdao

For example, you might have a core sleep period from 2-5am, and then three or four shorter naps spread throughout the day.

例如，您可以安排一个从凌晨2点到5点的核心睡眠阶段，然后其余的时间进行3到4次小睡。

youdao

This isn’t just my opinion but also the observation of others who’ve tried including core sleep from the beginning — oversleeping is very common, which makes adaptation take longer.

这也不只是我的意见而且也是来源于很多的案例观测的结论。

youdao

"We aren't sure why activity primes your body for sleep so well, but it's likely a combination of factors, including lowering your core body temperature, increasing the sleep-promoting hormone melatonin and supporting a biological need to restore energy levels and repair cells and tissues when you sleep, " Cardinal says.

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