Trapped in an Empty Office at Night Meaning & Interpretation

"I was sitting alone in an office. It was late, and the building was very quiet. I looked around and saw many empty desks. The computers were turned on, but nobody was using them. I checked the clock on the wall, but it had stopped at 6:00. I stood up and walked through the office. The lights above me turned off one by one as I walked. I went to the main door, but it was locked. I tried to open it several times, but it would not move. Then I heard a phone ringing from one of the empty desks. I walked over and picked it up. Nobody spoke. I could only hear a quiet sound on the other end. I put the phone down and turned around. Suddenly, all the desks were gone. The office was completely empty. I saw a door at the other end of the room and opened it. Behind the door was another office that looked exactly the same. I became very confused. I did not know where I was or how to get out. Then I heard my phone ringing beside me. I reached for it and suddenly woke up in my bed."