Understanding your sleepy cat is important because cats sleep two-thirds of their life away. That's 16 hours or more each day; that's more than any other mammal, except for the opossum and some bats.
Your Sleepy Cat
Why do cats sleep so much? Several issues are involved. Predators that have few natural enemies can afford to sleep for longer periods of time. Also, the need for sleep increases in direct proportion to the amount of energy required. Being a predator, the cat has extraordinary energy needs for hunting, but usually uses enormous bursts of energy to stalk, pounce, and wrestle that toy mouse into submission.
The sleep activity of cats, like that of people and many other mammals, is characterized by two patterns of brain activity. This activity has been measured experimentally with an electroencephalograph (EEG) that records waves or pulses of brain activity on a graph.
When awake, the cat's brain broadcasts little bunched-together irregular peaks. But when dozing, the cat's brain produces long, irregular waves called slow-wave sleep, which usually lasts 15 to 30 minutes total. As he dozes, a cat generally lies with his head raised and paws tucked beneath him. Sometimes he actually sleeps sitting up, in which case his muscles stiffen to hold him upright. This way he's ready to spring into action at a moment's notice.
When kitty moves from light into a deep sleep, his body relaxes; he stretches out and rolls to one side. His brain patterns change and the waves become smaller and closer together, and are very similar to his waking patterns. However, cats are fully relaxed and hard to awaken during deep sleep (referred to as rapid sleep because of the quick brain wave movement). This phase usually lasts only about five minutes, and the cat then returns to slow-wave sleep and thereafter alternates between the two until he finally wakes up. Interestingly, kittens fall directly into deep rapid sleep without this alternating pattern, until they're about a month old.
Cats and Dreams
Cats exhibit the same stages of sleep as humans do, and humans dream during rapid sleep. Therefore many scientists assume cats dream just as humans do, but we can only guess the subject matter. When those paws twitch or cat-calls spill from the sleeping kitty, perhaps he's chasing dream mice!
Cat's continue to sense sounds and scents most of the time they are asleep. This means they can awaken quickly at the squeak or scent of a nearby rodent. Slower wake-up times are characterized by a predictable pattern of blinking, yawning and stretching. First the forelegs, then back, and finally rear legs are flexed. Most cats also groom themselves briefly upon first awakening.
While humans may sleep in marathon eight-hour (or longer) sessions, cat sleep commonly consists of short and long naps throughout the day. Habits vary between cats and geriatric and young kittens sleep more than adults. Sleep time increases on cold, rainy or cloudy days.
Discovery of REM Sleep in Cats
In 1958, William Dement discovered REM sleep in cats. Around the same time, French physiologist Michael Jouvet ushered in what has been called the golden age of sleep research. Jouvet called REM sleep paradoxical sleep. Jouvet chose the term paradoxical (which means strange or contradictory) because during this phase of sleep animals showed biological signs similar to those of an awake animal. It was theorized that perhaps they were acting out their dreams in their sleep.
Cats are most active at daybreak and sundown. That's why kitties seem to love playing at these times and can pester tired owners with wake-up calls and bouts of activity. But they typically adapt to the humans they love, sleeping on the owner's schedule. That way, they sleep when you are gone and spend more awake time when you are home.