Sungmin, in Japan once didn't sleep to let the other members sleep peacefully:

This is how the conversation went:

Heechul: One Time we were in Japan for a concert, I shared a room 
with Sungmin, Super Junior's Sungmin. But he snored a little, and so the next day I told him, "Yah, Sungmin You snored a bit last night."
Sungmin: Ah Hyung, really?
Heechul: That night the eintire time there wasn't any snoring. So the next day I told him, "Sungmin, I didn't hear you snore anymore."
Sungmin: Ah , Yeah Hyung... I didn't sleep at all, I worried I would let you stay up because of my Snoring.