Hummingbirds do not sleep the way other birds or animals do. At night, their sleep is compared to a state of hibernation.  Their body temperature, heart rate, and breathing rate drop significantly. This is called torpor (TOR-per). In the morning, all of these rates return to normal, and the hummingbird wakes up.

One of the most distinguishing characteristics of a hummingbird is its gorget (GOR-jet). The gorget is the bright, almost glowing color on the throats of males, and some females. However, if the bird is not facing a light source, its throat appears to be black. This glowing - called iridescence - is created the same way that light reflects in a prisim yo make a rainbow. The outer parts of the feathers on the gorget have little air bubbles that reflect some light. However, these parts of the feathers are actually flat so the light is only reflected one way, which is why the throat looks black when the light source is not directly on the gorget. Some hummingbirds, such as the Anna's Hummingbird, have this iridescence all over their heads instead of on their throats alone.