And in far less horrific, but still not exactly comforting news, it turns out that dolphins only sleep with half their brains ...

The announcement came after US President Donald Trump said he would "get Greenland", saying the autonomous Danish territory ...

Animals have fascinating sleeping patterns adapted to survival. Dolphins sleep with one eye open, giraffes get about 20 minutes of sleep a day, and sea otters hold hands to avoid drifting apart.

Not to worry—shut-eye comes easily to these aquatic mammals Explore Subscribe Newsletters Content Licensing Our Partners Terms of Use © 2025 Smithsonian Magazine ...

From Dr Michael Breus’s chronotype animals to Dr Nerina Ramlakhan’s ‘sensitive’ and ‘Martini’ sliding scale, there are many ways to categorise the way we sleep. But which ones best ...