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Most biologic and psychological processes
vary according to a natural rhythm. Many of these functions
have a cycle of about one day and are called circadian rhythms.
Circadian rhythms influence
body temperature, sleep and wakefulness, and a variety of
hormonal changes. Sunlight and other time cues help to set
circadian cycles so that they are consistent from day to day.
Even if we didn't have time cues from our environment, fluctuations
in circadian rhythms would continue to occur within a period
of a little more than one day (generally about 25 hours).
As a consequence of this we "reset" our internal
clocks on a daily basis by going to sleep at the same time
each night and awakening at the same time each day.
Circadian rhythms are
coordinated by a group of cells at the base of the brain called
the suprachiasmatic nucleus (SCN). The SCN has connections
with other parts of the brain that control the body's temperature,
release of hormones, and many other automatic functions. A
pathway runs from the eye directly to the SCN which explains
why light seems to be the most important cue in terms of "setting"
our internal clock. Interestingly, blind people often report
problems with circadian rhythms, since they cannot get the
visual time cues that sighted people can get by just turning
on a light. Other factors that may affect the SCN and the
setting of our circadian clock include changes in our body
temperature caused by environmental changes or by the presence
of fever that accompanies different illnesses and by the effects
of certain medications.
In healthy people, the
various circadian rhythms are "in tune" like the
many instruments of an orchestra. Body temperature, for example
starts to rise during the last hours of sleep, just before
waking up in the early morning. At night, body temperature
starts to fall which aids in sleep onset. A drop in temperature
also occurs in most people between 2:00 and 4:00 p.m., which
may explain why people feel sleepy in the early afternoon
and why many people take an afternoon "siesta."
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Follow a regular
schedule of going to bed and waking up in the morning
all week long. Do not "sleep in" on weekends
or holidays. |
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Avoid daytime
naps, even if you miss sleep the previous night. |
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Avoid drinking
caffeine containing beverages such as coffee, tea or
colas after 7:00 p.m. Chocolate also contains caffeine. |
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Make sure your
sleeping environment is comfortable. This includes having
a quiet room, a comfortable bedroom temperature and
a comfortable bed. |
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Use your bed only
for sleep or intimacy with your significant other. |
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Do not eat meals
in bed or conduct business from bed. |
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Do not watch TV
or read in bed if you experience any problems falling
or staying asleep. |
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Associate your
bed with sleeping, relaxation and comfort. |
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Engage in moderate
exercise in the early part of the day; try to avoid
strenuous physical activity within three hours of going
to sleep. |
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Develop a positive
attitude about sleep. |
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Get out of bed
and engage in a relaxing activity if you are unable
to fall asleep within 15 to 20 minutes of turning out
the lights. |
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Do not use your
time in bed to worry about problems. Sleep is not something
that you can accomplish by "hard work." It
will occur naturally if you allow it to. |
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