translation.en: OK. So we've had three explanations for why we might sleep, and I think the important thing to realize is that the details will vary, and it's probable we sleep for multiple different reasons.
translation.zh: 好，这样我们有三种解释，为什么我们要睡觉， 我认为我们需要意识到 细节是多样的，我们可能是有很多不同的原因要睡觉。