The Joys of Blackout Sleep

The curtains in my new room are thick, made of an oddly waxy material, almost like rubber. When I turn the light out to go to sleep, this plunges my room into an almost absolute darkness. If I wake in the night and need to use the bathroom (I love that phrase) this necessitates a dangerous trip across the vastness of my bedroom floor, stubbing toes and sliding on too many comics and supplements from the Sunday papers.
Back at the bedsit I would tend to wake with the light, so I was often quite alert by the time the alarm went off. Here though, I am unaware of the dawn behind the closed curtains, and so I wake with the alarm, to that harsh intrusion into dreams that have been forgotten by the time I finish my shower. Sleep back in the bedsit was like lying in the shallows of a summer pool. Here it is like sinking into the depths of a lake that is rumoured to be bottomless. I wonder, without the alarm, exactly how long would I sleep for?