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tions follow
similar circadian rhythms. Both internal controls, from the hypothalamus in the brain, and external
controls such as clocks, meal times, light and dark, and the seasonal changes direct us to 24-hour
circadian rhythms. If individuals live in caves with artificial light, but no clock, eating and sleeping
whenever they want, circadian rhythms tend to occur in 25-hour cycles.
People usually fall into a rhythm between 24 and 28 hours long, although sleep—wake cycles of up
to 50 hours have been observed. Excessively long circadian rhythms can play havoc with one’s life,
causing one to be unable to sleep at an appropriate hour or to feel sleepy part of the normal working
day. The results can be job loss and interpersonal conflict. Such afflictions can be interpreted as
sleep-onset insomnia and/or excessive sleepiness. Treatment of such sleep disorders centers on
enforcing wakefulness at certain times.
Along with “autonomic” storms of REM sleep that are most intense in the morning hours, changes
in circadian rhythms result in a lowering of body temperature. One medical consequence of this
“vulnerable” state is the reported high incidence of cardiac failures and heart attacks in early
morning hours. “Jet lag” is also an effect of biological circadian rhythms falling out of synchrony
with local time as we travel east or west across time zones. The traveler develops a double circadian
rhythm, the new one added to the old. This leads to double peaks and valleys of energy. Over a few
days, the new circadian rhythm takes over as the body and brain reset their biological clock to local
time.
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CHAPTER 6: MIND, CONSCIOUSNESS, AND ALTERED STATES
The Stuff of Which Dreams Are Made
Throughout history, and probably prehistory as well, humans have thought that dreams have
special significance, that they have a divine source, predict future events, or prescribe a course of
action. A primary duty of wise elders in many cultures was to interpret dreams. One wonders how
preliterate tribes react to their dreams, to these images that invade their sleep. Perhaps they think
that some alien being has taken over their body or that they are receiving a message from the spirits
of the earth or the demons of the
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