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Today i was in my physics lab doing an experiment on simple pendulum. Suddenly my friend fell down to the ground uncounicouseely. He went down fully it took him like 5 minutes or more than it to wake up. In the lunch break i asked him about his experince about it. He said he blacked out and when he fell down he said saw small dots. He also said that his head was getting heavy. I could also feel the heaviness around the room. Any suggestions what this could be?