In Roman insulae, they often slept in windowless rooms. Many of them also woke before sunrise. They were generally woken by slaves, roosters and the increasing noise from people outside.
I suppose I jumped the gun, or misread. I responded with 'apartments' not noticing that you had said 'rooms'. Most Roman apartments had windows, cubicula often did, but only irregularly; more of a coin flip, with better-quality apartments more likely to have windows in the cubicula. I can send a book your way if you're interested in the details; otherwise, just accept this mea culpa.