Sleep!

Sleep!

An interesting article about the evolutionary origins of sleeping:

Birds appear to be able to defend against predators with a variation on this strategy. When they feel safe, they sleep with their entire brains shut down, as humans do. But when they sense threats, they keep half their brains awake.

Dr. Lima and his colleagues have demonstrated this strategy in action with several bird species, including ducks. 'All we did was put our ducks in a row, quite literally,' said Niels Rattenborg, a colleague of Dr. Lima's, now at the Max Planck Institute for Ornithology in Germany. 'The ducks on the interior slept more with both eyes closed, and the ducks on the edge slept with one eye open. And they used the eye that was facing away from the other birds.'

To give each side of the brain enough rest, the ducks at the ends of the row would stand up from time to time, turn around and sit down again. This allowed them to switch eyes and let the waking half of the brain go to sleep.