Dislocated Time and Space

In my senior year of high school, I lived twice as long as others. After falling asleep every night, I will enter a parallel time and space and learn again the knowledge I learned during the day. Relying on this secret, I became a good student in the eyes of the teacher. Until that day, Country M announced that it had successfully developed the "elixir of immortality". From that night on, parallel time and space changed. At two o'clock in the morning, the dormitory building was completely silent, and there was no one under the roommate's quilt. Something with gray-white eyes wandered the hallways, calling my name over and over again. What's even scarier is that I found a note under the pillow - my handwriting, which said: "You must leave the dormitory before four o'clock in the morning." I don't remember writing it. But I couldn't tell whether those things with gray-white eyes were in parallel time and space, or had followed me back.