達旦不瞑

I'm reminded of the passage in 《養生論》where it talks about the power of emotions, in particular this line：“夜分而坐，則低迷思寐；內懷段憂，則達旦不瞑。” (loose translation: if one stays up late to work, he will feel quite sleepy; but if one's breast is full of worries, his eyes will be open all night) 

In my case what it takes is a stimulating lecture and good conversation!