Birds have a nifty tendon arrangement in their legs which help them sleep when they are perched.
The flexor tendon from the muscle in the thigh reaches down over the knee, continues down the leg, round the ankle and then under the toes.
This arrangement means that, at rest, the bird’s body weight causes the bird to bend its knee and pull the tendon tight, so closing the claws.
Apparently this mechanism is so effective that dead birds have been found grasping their perches long after they have died.
Yes, birds do sleep. Not only that, but some do it standing on one leg. And even more surprising, may be hypnotised into sleep at will. My myna bird was.
If you wish to try it, bring your eyes close to the cage, and use the hypnotist’s ‘your eyes are getting heavier” principles (not spoken) on your own eyes. Act as if you are gradually falling asleep and the bird will follow you, finally holding one leg up under its belly, tucking its head under its wing and falling into a deep sleep.
What’s more, most pet bird owners know that all you need to do to make your pet fall asleep is to cover the cage with a blanket to simulate night.
Birds do sleep, usually in a series of short “power naps”. Swifts are famous for sleeping on the wing. Since most birds rely on vision, bedtime is usually at night, apart from nocturnal species, of course.
The sleeping habits of waders, however, are ruled by the tides rather than the sun.
Some other species are easily fooled by artificial light.
Brightly lit city areas can give songbirds insomnia. A floodlit racetrack near my home gives an all-night dawn effect on the horizon, causing robins and blackbirds to sing continuously from 2am onwards.
Unfortunately, we don’t know whether it tires them out as much as it does us.