Hi, about a month ago while I was on nights, I was doing a level 3 observation (watching a patient for an hour while asleep) it was very quite on the ward, all of a sudden I heard my voice inside my head sound very loud, slow and deep. I felt a bit nauseous, I felt an intense fear, and my depth perception felt off, I felt drowsy. This lasted around 3-4 minutes possibly slightly longer, it really worried me. Any idea what this could be?