Working in a nap can be difficult for birds as well as humans. And naps are important. Even a six minute nap improves a human’s memory. Pigeons need naps too but often miss them. A pigeon can’t take a power nap if there is a predator in the area. But they take naps, as do many other birds and mammals. In nature, napping is normal. In fact, it is the norm everywhere except modern industrialized clusters of humans. And, as we discussed recently, the sleep of birds resembles that of mammals even to the extent of dreaming.
What we call “deep sleep” is that phase of sleeping known as slow wave sleep (SWS) in which neurons oscillate in long and slow waves. Rapid Eye Movement (REM) sleep is not as deep and it is when dreams happen. More REM occurs at the end of the sleep cycle and more SWS at the beginning.
Scientists will do all sorts of things to experimental subjects, including keeping pigeons awake when they want to be napping. In a recent study at the Max Plank Institute of Ornithology they deprived pigeons of their usual late afternoon naps to see if they made up for it at night. Making up for lost sleep involves spending more time in SWS and even longer and slower wave patterns.
Just as in mammals, the scientists discovered that sleep deprived pigeons make up for the daytime sleep loss by sleeping more deeply at night. Mammals and birds, with entirely different brain structures, seem to regulate sleep in the same way.
Just more evidence that having a large cortex may not be as big a deal as we thought. To put it in the more elegant words of a nuclear physicist,
There is separation in Life but
there is no separateness.
We are all connected.
– David Bohm
The full citation for the article reporting on pigeon napping:
Dolores Martinez-Gonzalez, John A. Lesku and Niels C. Rattenborg
Increased EEG spectral power density during sleep following short-term deprivation in pigeons (Columba livia): evidence for avian sleep homeostasis.
Journal of Sleep Research (2008), Online Early Articles, February 27, 2008
Here is an abstract of the article.