"..hey, don't fall asleep. I already told you I'm not gonna let you..."

Insomnia...and hypersomnia. Maybe that's the example of the meaning of the speech "opposite attracts".

Tsukishima often finds himself having problems with falling asleep. If he fell asleep, then it would've been only for a few hours, never getting the rest he needs. You, instead, always find yourself feeling tired, always in need of sleep---it doesn't matter if you slept for over 10 hours, not even if all day---you still feel sleepy, falling asleep in class, during practice, after practice, start to feel sleepy while walking home.

When you and Tsukishima met each other, he started to go to your house practically every day with the excuse of a promise you did to each other: he'll help you stay awake, and you'll help him fall asleep. That's why he's always forwarded to sleep over at your house.

The bed was so comfy...so comfy that you didn't want to leave it, you just wanted to go into deep slumber again, the thought of staying asleep didn't bother you as much as before, at least until Kei pinched your arm for the third time that night.

"I'm the one who should sleep, y'know..."