Do animals have sleep disorders?

Sleep Disorders are common in humans, but many scientists wonder whether these same problems can occur in animals as well. There is some research to suggest that the answer is “yes.” Animals are in many ways very much like human children. Like our children they wet in their sleep, “talk” in their sleep and often have disturbing dreams. They have rhythmic head movements and many other symptoms that we find in children.

Dr. John Hedricks and Adrian Morrison from the School of Veterinary Medicine, University of Pennsylvania in Philadelphia determined that certain diseases were primarily associated with the sleep states in animals. They emphasized that because so much in this area still remains unclear, animal models were very important for studies of sleep disorders. The physiology of sleep in animals is similar to that of humans. For example, the so-called phasic phenomena (sudden periods or sudden changes) in REM sleep are the same in animals. Episodic muscle twitches of distal parts are also much more apparent in animals. In fact, they are so intense that animals move in their sleep. Every veterinarian that was asked whether dogs or cats dream confirmed twitching of limbs, facial muscles and vocalizations which periodically interrupts the animal’s peaceful sleep, suggesting that it is actually dreaming. Researchers and doctors who work with animals state that the effect of dreams on an animal’s behavior during daytime is similar to the effect in humans.

Observations suggest that REM sleep is characterized by a highly activated brain. Visual activity, motor activity, and metabolic activity rise during these periods. Eye movements in sleep have a striking resemblance to eye movements in wakefulness. For example, when the cat is confronted with another stimuli, its eyes move exactly the same way as in dreams, which suggests that it is actually seeing something in its dreams.

Patterns of sleep in animals are different in each species, but they are cyclical and have the same stages of development by age. Predators spend a great percentage of the 24-hour period sleeping and animals with secure sleeping places sleep more than animals that sleep in the open. Some animals, like horses, have skeletal adaptations that allow them to sleep standing up. However, they do not achieve REM sleep in this position. To sleep in a REM stage, they must and lie down. Other animals, such as dolphins, have different adaptations. Dolphins sleep in one half of the brain, while the other side is alert.

Sleep and Health Journal