When you are locked in your room during the early part of the game you need to check the calendar to the right of the door every day.
The game seems to count you sleeping / dreaming as the end of a day so every time you have the ability to walk around the room freely just make sure you go and inspect the calendar.
Unfortunately there is no indicator or sound to show that you have got close enough for it to count but fortunately this is very early on in the game so if you miss it, it is easy enough to do again.
The trophy popped for me when I was finally released from the room in the "real world".