Why do we talk about catnaps?
Because cats indulge in brief periods of
light sleep so frequently. In fact, these short naps are so common
in cats and so rare in healthy humans that it is not exaggerating
to say that cats and people have a fundamentally different sleep
pattern. Unless human adults have been kept awake half the night,
or are sick or extremely elderly, they do not indulge in brief
naps. They limit their sleeping time to a single prolonged period
of approximately eight hours each night. By comparison, cats are
super-sleepers, clocking up a total, in twenty-four hours, of about
sixteen hours, or twice the human period.
This means that a nineyear-old cat
approaching the end of its life has only been awake for a total of
about three years. This is not the case in most other mammals and
puts the cat into a special category – that of the refined
killer.
The cat is so efficient at obtaining its
highly nutritious food that it has evolved time to spare, using
this time to sleep and, apparently, to dream. Other carnivores,
such as dogs and mongooses, have to spend much more time scurrying
round, searching and chasing. The cat sits and waits, stalks a
little, kills and eats, and then dozes off like a wellfed gourmet.
Nothing falls asleep quite so easily as a cat. There are three
types of feline sleep: the brief nap, the longer light sleep and
the deep sleep. The light sleep and the deep sleep alternate in
characteristic bouts. When the animal settles down for more than a
nap, it floats off into a phase of light sleep which lasts for
about half an hour. Then the cat sinks further into slumber and,
for six to seven minutes, experiences deep sleep. After this it
returns to another bout of thirty minutes of light sleep, and so on
until it eventually wakes up. During the periods of deep sleep the
cat's body relaxes so much that it usually rolls over on to its
side and this is the time when it appears to be dreaming, with
frequent twitchings and quivering of ears, paws and tail. The mouth
may make sucking movements and there are even occasional
vocalizations, such as growls, purrs and general mutterings.
There are also bursts of rapid eye movement,
but throughout all this the cat's trunk remains immobile and
totally relaxed. At the start of its life, as a very young kitten
during its first month, it experiences only this deep type of sleep
which lasts for a total of about twelve hours out of every
twenty-four. After the first month the kittens rapidly switch to
the adult pattern.