Albatrosses are seabirds known for their expansive wingspans and ability to traverse vast ocean distances. They do sleep, but their patterns are uniquely adapted to their life at sea. They employ various strategies to obtain rest, whether soaring or settling on the water, enabling them to sustain their incredible journeys.
Sleeping While Soaring
Albatrosses can sleep in flight using unihemispheric slow-wave sleep (USWS). This specialized adaptation allows one half of their brain to enter a deep sleep state while the other remains active and alert. The active hemisphere maintains flight control and awareness of surroundings, including potential obstacles or predators. This partial sleep means one eye stays open while the other closes.
During USWS, albatrosses glide effortlessly using dynamic soaring, riding wind gradients to gain lift with minimal muscle effort. Their wings have a unique shoulder-lock mechanism, keeping them outstretched without constant muscle expenditure, conserving energy during these aerial naps. While direct brain activity measurements on flying albatrosses are challenging, studies on similar long-distance flyers, like frigatebirds, have confirmed this in-flight sleep using electroencephalography (EEG), supporting the theory for albatrosses.
Resting on Water
Albatrosses also frequently rest on the ocean’s surface, providing a more complete form of rest than their in-flight naps. They typically settle on the water during calm weather or at night when foraging activity is reduced.
On the water, albatrosses engage in bilateral slow-wave sleep, resting both brain hemispheres simultaneously. This allows for deeper, more restorative sleep than fragmented in-flight sleep. Tracking studies show they can spend several hours each night floating. However, resting on water carries risks, such as increased vulnerability to predators, limiting their surface duration.
The Purpose of Unique Sleep
Albatross sleep patterns are tied to their migratory lifestyle and the demands of their vast oceanic environment. These adaptations allow them to maximize time spent foraging and traveling across immense distances. Some Laysan albatrosses fly nearly 50,000 miles over two months without touching land.
USWS allows albatrosses to rest without interrupting continuous flight, conserving energy. Their energy-efficient gliding and in-flight napping enable them to traverse vast stretches of open water where no suitable resting places exist. This strategy helps them avoid the high energy cost of taking off and landing, given their large size and dependence on wind for efficient flight. These specialized sleep behaviors provide an evolutionary advantage, allowing albatrosses to thrive in an environment that demands constant movement and vigilance.