Nick is a night person.  He likes to sit alone and know that he’s awake when most people near him are asleep.  I like doing the same thing – sitting and knowing I’m awake when others are asleep – in the morning.  I am a morning person.  I wake up at 6am, maybe dozing an extra ten minutes on occasion.  Even more rarely, I sleep in.  The latest I have ever slept in was noon, and before that ten am was my latest by determined effort.  I cannot comfortably stay in bed later than 8, unless I was up super late the night before.  Nick is uncomfortable being up and awake before 8 am, and he prefers 10.  I don’t know how we live together, I really don’t.  For work nights, I like to be in bed by ten.  I’ll read or we’ll talk for a little bit, but lights are out for me by 10:30.  Because I get up at 6, and I want to be happy when I do that, not snarly and confused and angry.  Nick then stays up for another few hours, till 2.  Earlier in our marriage he’d stay up till 3, 4am.
I remember vividly one night, I had gone to bed at say 11pm, and had woken up at 3:45am rather suddenly.  I stretched a leg out – no contact.  I rolled over and stretched out an arm, swiping back and forth to see if he was somehow tucked under a pillow or scrunched under a blanket.  Nothing.  I rolled the opposite direction to look to the door, and it was outlined in refracted light from the living room.  Sudden fear and anger suffused my sleep-muddled mind.  I flipped the blankets off of me with more force than was necessary, and shuffled out into the blinding glare of a single soft white  bulb from across the room, arms folded and tightly tucked to my ribs.  Shuffle shuffle. . . eyes scan the room only to alight on. . . Nick.  Sitting at his computer, also outlined by light.  This light was blue, and came from bolts of magefire being flung across the screen.  I believe I said, “What the hell?”  Only, I was still moderately asleep so it sounded like, “wha thahell?”  He turned around.  “It’s ****ing quarter of 4 in the morning, ***hole.  Wha tha hell?”  I get very profane when woken out of a deep sleep by the sudden knowledge that my bedmate is missing.  His answer was both profound and elegant, ” Huh?”  Mine was equal in profundity and beauty, “I hate you.”  (don’t be concerned that I tell my husband I hate him on a regular basis.  It is less a true statement than an expression of passing emotion.  No, I never left kindergarten.)
After that lovely interlude, we chose a nice curfew for him that both allowed him the nighttime like he craves and allowed me to not mumbleyell profanities at him at 0 dark 30.  He comes to bed at 2.