The ending is one of the scariest moments in cinema for me. I remember watching it in the middle of the night on PBS I think. I was absolutely terrified about what was in that room with him as he was aged and kept looking over his shoulder.
For me it was being maybe 13 and tuning in to the last half of Lord of the Flies at about 1am. Those kids abandoned on a lonely island, followed by the rescuer showing up, followed by credits, followed by the national anthem and test colour bars will forever be burned into my brain.