A new study conducted at the Max-Planck Institute for Ornithology in
Seewiesen, Germany found that pigeons make up for sleep loss in a fashion
similar to that of humans.

Birds experience 2 sleep states that are the same as the 2 experienced in
humans; deep slow wave sleep (SWS), and Rapid Eye Movement (REM) sleep.
Birds are the only other taxonomic group, other than mammals, to have both
states of sleep. The amount of slow waves experienced during SWS is directly
correlated to the depth of sleep—more waves equal deeper sleep.

During the study, researchers found that pigeons recover from periods of
sleep loss by increasing the amount of slow waves during SWS, meaning they
slept more deeply. This means pigeons can make up for sleep loss without
sleeping for a longer amount of time. Humans make up for sleep loss in this
same way.

The findings of this study further backs the theory that researchers can
learn more about the function of sleep in humans by studying sleep in birds.

The study can be found online in the Journal of Sleep Research.