How does an ostrich sleep? Almost imperceptibly, it seems. Even though an ostrich might be sound asleep, it can look wide awake or, at most, a little drowsy. John Lesku from the Max Planck Institute of Ornithology discovered this by fitting six ostrichers with “Neurologgers”, electrode-laden helmets that measures their temperature, brain activity, eye movements and neck muscle contractions.

The video above shows three of the birds cycling through two different types of sleep. The first is called ‘slow wave sleep’ or SWS, where the ostriches’ brain waves are slow and strong. Even though this is typically known as deep sleep, the birds look alert. They stay still, but their eyes are open and their necks upright. Nonetheless, the