Scientists believe the birds dream of singing to help them hone a range of different tunes. The new finding emerged from a study of the electrical brain activity of zebra finches.
A team from the University of Chicago found that sleeping birds fired their neurons in complex patterns similar to those produced when the birds were awake and singing.
Young birds learn to sing by listening to adults and then practise by listening to their own attempts. The research suggests the songbirds store a song after hearing it, then rehearse it later in their sleep.
Sweet dreams
Professor Daniel Margoliash, who led the study, said: "From our data, we suspect the songbird dreams of singing.
The study, reported in the journal Science, suggests that sleep plays a key role in the learning process. Studying how birds learn to sing could reveal clues about how people learn speech.
The professor added: "Neurobiologists have often found that lessons learned from weird and wonderful animals apply to all animals.
Brain waves
"The beautiful songs of birds could have much to teach us about how we learn."
The US team used tiny recording devices to measure the activity of individual brain cells in four zebra finches.
They recorded firing patterns of separate cells in musical areas of the Australian songbird's brain.
When the recording was played back to a sleeping bird, the neurons in its brain fired in a pattern identical to that which accompanied singing, although the bird produced no sound.