Bruma castle jail is bugged.

[Velamont]

You can't serve your sentence in that jail so you can't complete one of the quests. (Unless you are are willing to escape)

[OMG Laserguns Pew Pew Pew!]

I'm having the exact same problem, trying to complete Two Sides of the Coin and can't serve out my time in jail because it will crash to desktop as soon I try to sleep.

[Draco1122]

Same bug

[il mio nome è nessuno]

I have a bug when i try do this quest at jail too. But, instead crash, when i tried sleep, game freezes. I checked mods installed, if there is a link but i don't see. It's really funny, that devs dare do a game and don't search at any moment to say, if we fix bugs in game, it will be a very good idea. They just do a game and don't care about issues. After it's bethesda, it's normal. Now players pray to have no bugs or very few.

[il mio nome è nessuno]

But you can fix this bug with command console 'ghost' to escape jail instead sleep, and type 'walk' at the chest where you have your equipments. It unlocked script for me. After you can continue the quest.

[Basarab Laiota]

i did this quest by breaking out of prison lol
it was more fun