Riodan- His sleep heaviness or lightness depends on the context of his sleeping. If he feels safe and happy in a sleeping place he'll be a lot more likely to sleep heavily there. On the other hand if he's on...

campaign or in a potentially dangerous place he tends to sleep much more lightly. This said if he's dog tired he'll sleep like a rock or in pain he'll sleep fitfully ect.

He also has the ability to set a sort of internal alarm clock for himself. He can plan to wake up a certain point if he thinks about it before going off to sleep. Since he's living in a pre-industrial world...

his "alarm clock" settings are like before dawn, dawn, ect.

sleeping positions- he tends to sleep on his sides or his back. He's totally happy to spoon with someone, however in canon I don't know if he ever gets the chance. He'll totally wrap himself around a...

pillow or blanket folds. He needs about five-six hours of sleep to function well. It's a flaw of his.

I guess this sort answer that happens when one "lives" with someone for like 16 years lol.

For the first few books of the series, Viktor no longer needs to sleep after he is cursed by Mamaan Juma