Sperm whales sleep very little. On average, they spend 7% of their daytime sleeping. By comparison, a human spends more than 30% of their day sleeping. When they fall asleep for a few minutes, sperm whales position themselves... vertically! A posture that we would not have imagined possible coming from these giants of the seas which can measure up to 16 meters. This position makes it easier for cetaceans to come to the surface to take a breath.