You spend most of your day vertical, and only go horizontal when you want to rest. Sperm whales are the opposite: they spend most of their day horizontal, and actually tilt upright to sleep. If you think that's a strange sight, you should hear what the first researchers to find it thought.
The Upright Cetaceans Brigade
Sleep With One Eye Open
8 Strange Animal Sleeping Habits
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Curiosity StaffJuly 22, 2017
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