And yet, most of us
know little about sleep.
People often think
of sleep as a time when we rest and the brain becomes
less active, but in reality a great deal of activity occurs
in both the body and the brain when we sleep. Sleep doesn't
turn off the systems of the body completely - in fact
some of them function more actively once we fall asleep.
How Much Sleep do we Need?
The amount of sleep
needed by individuals varies a great deal. There is no
set 'normal' amount of sleep that each of us requires.
However the amount you personally need is usually quite
regular and although you may sleep for different lengths
of time on different nights over a week, your average
is likely to remain constant.
Many of us are familiar
with the '8 hours of sleep' that seems to be the prescribed
amount usually quoted, although most people seem to sleep
naturally for somewhere around 7 hours; anywhere between
3 and 10 hours can be considered a good night's sleep,
depending on the person.
Sleep researchers have
defined people who need 6 or fewer hours of sleep per
night as short sleepers and people needing 9 or more hours,
long sleepers.
Some people do seem
to get by quite happily on very little sleep, and how
much you need varies from person to person and your own
sleep needs may also change at different times. For example,
we often need more sleep if we are suffering from:
Infants and Children:
Newborns require around 16 hours of sleep per day. This
decreases to about 14 hours from the age of 6 months to
3 years. Young children tend to get their sleep quota
from a combination of naps and nighttime sleep.
Adolescents:
This age group requires around 9 hours of sleep per night.
Sleep is vital for teenagers because their bodies release
growth hormones essential for development to adulthood.
Adults - For
most adults 7 to 8 hours per night is the often quoted
optimal level of sleep time, although in reality this
can range from 4 hours to 10 hours depending on the individual.
Pregnant Women:
Women in the first trimester (3 months) of their pregnancy,
and often throughout the entire pregnancy require significantly
more sleep than they usually have.
Do We Need Less Sleep as We Get
Older?
Sleep patterns do alter
as we get older with older, people tending to sleep more
lightly. As our bodies age our quality of sleep becomes
poorer and becomes lighter, less efficient and unfortunately
less restful.
As we age we experience
less delta sleep, which is the deepest and most restful
sleep phase we experience. Delta sleep is also associated
with bodily growth and recovery. This decrease in delta
sleep is experienced by men from around the age of 50
and for women at about 60 years of age. People in this
age group often experience being easily affected by noise
or other outside factors that a younger person would be
able to sleep through.
The actual amount of
sleep time on average does not decrease much between the
ages of 20 and 70; the problem is that the incidence of
sleep problems and disturbances does. Sleep time becomes
lost because of outside interruptions and brief periods
of wakefulness.
Some older people experience
literally hundreds of short awakenings per night - sometimes
just for 15 seconds or less. These short awakenings can
lead the person to believe they have been awake all night
even though they haven't been. Older people may also take
more naps during the day which can affect the quality
of their sleep.
What Happens if
We Don't Get Enough Sleep
Missing one night of
sleep isn't too bad for you. If you have something important
happening the next day, like a job interview or something
else mildly stressful, then it is only natural to experience
some difficulty sleeping. Usually the adrenaline we produced
on the big day kicks in, keeps us going and hopefully
gets us through.
If we experience poor
sleep for several nights in a row then we start to feel
very tired and lose motivation to do much. Our attention
span can suffer particularly if we need to concentrate
on something that is quite boring, and our reactions may
become slower. Monotonous activities are particularly
difficult which is why the high incidence of road accidents
being caused by tired people falling asleep at the wheel.
Missing sleep on a
very regular basis, and other forms of chronic insomnia
leads to a definite decrease in day to day performance
and productivity; with serious problems concentrating
and remembering words, names and numbers.
Seemingly small sleep
losses that build up over days have a cumulative effect
and people suffering from sleep deprivation may start
to experience:
