Dolphin completely breaks the idea of sleep. Half of its brain stays awake 24/7, from birth until death. One side sleeps while the other stays alert enough to swim, breathe, and watch for danger. Then they switch sides. One eye closes. The other stays open. If both halves slept at once, the dolphin could drown. So imagine never fully shutting your mind off… for your entire life. That’s not resting. That’s survival mode forever.