Rengoku sleep headcannons for today...
1) He has a really hard time actually falling asleep unless he's holding you
2) Once he's out he is OUT, it's like sleeping next to a log
3) If you tried to roll away from him he would scoop you right back up
4) If you go to sleep before him then he will play with your hair (pet it, brush his finger through it) to wind down
5) He is so warm that y'all have to sleep with only a sheet or else you might overheat
Basically you are his personal teddy bear