10 birds that can sleep while flying, cover long distance without stopping

If you thought living creatures only slept in a state of rest, you may need to reconsider what you know about nature.

There are some birds that sleep while airborne, meaning they doze off while flying long distances!

This extraordinary ability, known as unihemispheric slow-wave sleep, allows certain birds to keep one half of their brain awake while the other rests. It helps them remain alert to predators, maintain flight direction and continue migrating across vast oceans and continents without stopping.

Scientists have studied this phenomenon in detail, and it has been observed most clearly in species that undertake long, non-stop migrations over water or open skies.

Here are 10 birds known for their ability to sleep while flying.

1. Alpine swift

The Alpine swift is one of the most remarkable aerial sleepers ever studied.

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Astonishing sleep fact: Researchers have recorded individuals staying airborne for up to 200 days, with only brief, controlled sleep phases occurring mid-flight. Even more extraordinary, they spend almost their entire non-breeding life in the air, landing only to nest.

During flight, their sleep is extremely fragmented, just seconds at a time, allowing them to maintain constant movement while still resting parts of the brain.

2. Common swift

Closely related to the Alpine swift, the common swift is another master of aerial life.

Studies suggest they can remain airborne for months at a time, using micro-sleep episodes while gliding. They are so adapted to flight that adult swifts rarely touch the ground outside breeding season.

Their sleep is believed to occur in short bursts during high-altitude gliding, reducing energy loss while maintaining navigation.

3. Frigatebird

Frigatebirds are known for their ocean-spanning flights.

Studies using brain activity sensors have shown they may sleep for only around 40 minutes per day during long flights, broken into ultra-short episodes while soaring over warm air currents.

They often sleep while gliding effortlessly, minimising wing flapping to conserve energy.

4. Great frigatebird

A close relative of the frigatebird, this species shares similar abilities.

Juvenile great frigatebirds can remain in flight for up to two months without landing, relying on unihemispheric sleep during long ocean crossings.

They prioritise sleep during soaring phases when they are most stable in the air.

5. Swainson’s thrush

Unlike ocean wanderers, Swainson’s thrush migrates at night over land.

During migration, it can engage in microsleeps lasting only seconds, allowing partial brain rest while continuing flight direction using instinct and magnetic cues.

These brief sleep states help it cover thousands of kilometres across the Americas.

6. Barn swallow

The barn swallow is a familiar sight across farms and rural landscapes.

Although most sleep occurs on land, evidence suggests barn swallows may enter partial sleep states during long migratory stretches, especially when flying in flocks that reduce predation risk.

This allows them to maintain energy efficiency during seasonal journeys.

7. Arctic tern

The Arctic tern is famous for having the longest migration on Earth.

Scientists believe Arctic terns rely heavily on sleep in flight during polar-to-polar journeys, although exact durations remain difficult to measure due to their extreme travel patterns.

Their annual migration can exceed 70,000 km, making efficient rest essential for survival.

8. Sooty shearwater

This seabird undertakes one of the longest recorded animal migrations.

Sooty shearwaters have been observed flying continuously over the Pacific, likely using short unihemispheric sleep phases during gliding flight over ocean winds.

They often follow circular migration routes that take them across entire ocean basins.

9. Manx shearwater

The Manx shearwater is a long-distance ocean traveller.

Astonishing sleep fact: Tracking data suggests it can remain at sea for days, possibly entering brief sleep episodes while gliding on air currents close to the ocean surface, reducing energy use during migration.

Their sleep pattern is thought to be highly adaptive to changing wind conditions.

10. Eurasian hobby

A fast and agile falcon, the Eurasian hobby migrates across continents.

While less studied than seabirds, behavioural research indicates that raptors like the Eurasian hobby may use short rest phases during high-altitude soaring, potentially involving unihemispheric sleep during long migratory flights.

Its ability to hunt on the wing suggests an exceptional level of aerial control even during rest periods.

How sleeping in flight actually works

All of these species rely on unihemispheric slow-wave sleep, a rare neurological adaptation that allows one half of the brain to rest and the other half to stay alert.

It also allows continuous flight navigation and protection from predators mid-air.

Some birds can even keep one eye open while the other rests, switching sides of the brain as needed.