As most people who have pulled an all-nighter will agree, lost sleep can leave us feeling foggy and far from our best. In some ways, birds respond similarly, often sleeping longer and more deeply after sleep loss. But unlike humans, birds can sleep with one eye open, keeping one half of the brain so mewhat alert while the other sleeps deeply. This balance between vigilance and deep sleep helps them stay aware of danger while still getting some much-needed shut-eye. ...read more read less