Gods know Nico had no idea how this schedule happened.
He would have nightmares. Hell, every demi-god did. But certain ones would leave him sleepless — scared at every little creak. Sure, he didn't like to admit to help. Nico almost hated being babied by anyone.
That's why it came a shock when he snuck out to the Hypnos cabin one night to see you. He just needed some form of comfort. Some way to have one peaceful night of sleep. But, of course, it became a routine.
Nico would have a nightmare, creep out of the Hades cabin, quietly slip into the Hypnos cabin, and see you waiting there for him half-awake. Nico felt a little bad for making you stay up just for someone like him. But as long as you insisted it was fine...
"I'm sorry." Nico quietly apologized, crawling up into the small bed with you. He was shaken, obviously, but he was so desperate for your comfort. So weak. He hated it, yet you were the only person who he felt comfortable enough with.