to the effects of caffeine, along with a mild physical and
psychological dependency. For example, tolerance to
caffeine-related sleep disruption disappears in about a
week among people who drink 3–4 cups of coffee daily.
The amount of caffeine it takes to reach this state is
highly variable.
Discontinuing caffeine among regular users causes
withdrawal symptoms. These can include headaches
(very common), irritability, nausea, fatigue, sleepiness,
inability to concentrate, and mild depression. Caffeine
withdrawal symptoms begin 12–24 hours after caffeine
is stopped. Withdrawal symptoms peak at around 48
hours, and can last up to five days. Tapering caffeine
use, for example cutting down on caffeine by the equiv-
alent of half a cup of coffee (about 50 mg) a day,
minimizes or eliminates withdrawal symptoms.
People who use more than about 500 mg (the
amount varies greatly among individuals) of caffeine
a day may develop a condition called caffeinism. Caf-
feinism produces unpleasant sensations, some of
which are similar to withdrawal symptoms. Symptoms
caffeine overuse include restlessness, irritability, nerv-
ousness, anxiety, muscle twitching, headaches, inabil-
ity to fall asleep, and a racing heart. Severe overuse of
caffeine can cause four psychiatric disorders recog-
nized by the American Psychiatric Association and
described in theDiagnostic and Statistical Manual of
Mental Disorders, Fourth Edition.Caffeine is consid-
ered the cause of these disorders after other causes
have been ruled out.
Caffeine intoxication: Usually the result of taking
caffeine pills (e.g., NoDoz), this condition causes
mental changes, rambling thoughts and speech,
irregular heart beat, and all symptoms associated
with overuse. In severe cases death can result from
ventricular fibrillation (unsynchronized contractions
of the ventricle of the heart).
Caffeine-induced anxiety disorder: Severe anxiety that
interferes with daily social interactions and occurs
after caffeine intoxication or heavy long-term use of
caffeine.
Caffeine-induced sleep disorder: An inability to sleep
that is so great it requires medical/psychiatric attention
and occurs after prolongedcaffeine consumption.
Non-specific caffeine-induced disorder: Disorders
not listed that are attributable to either acute or
long-term caffeine consumption.
Parental concerns
Children get most of their caffeine from soft
drinks. Parents should choose soft drinks that contain
little or no caffeine or replace soft drinks with water,
fruit juice, or low-fat milk. Adolescents are increas-
ingly using energy drinks and energy bars containing
caffeine. At the same time, many adolescents start
drinking coffee. Parents educate their children about
the effects of caffeine and encourage them to monitor
their caffeine consumption from all sources.
Accidental overdose from caffeine pills can be
fatal. Caffeine tablets, like all drugs, should be kept
out of reach of children. Children who accidentally eat
caffeine pills need immediate medical attention from a
physician or emergency room.Resources
BOOKS
Klosterman, Lorrie.The Facts About Caffeine. New York:
Marshall Cavendish Benchmark, 2006.
Mumaw, Stefan, and Wendy Lee Oldfield.Caffeine for the
Creative Mind: 250 Exercises to Wake Up Your Brain.
Cincinnati, OH: HOW Books, 2006.
Smith, Barry D., Uma Gupta, and B.S. Gupta, eds.Caffeine
and Activation Theory: Effects on Health and Behavior.
Boca Raton, FL: CRC Press, 2007.
Weinberg, Bennett Alan, and Bonnie K. Bealer.The World
of Caffeine: The Science and Culture of the World’s Most
Popular Drug. New York: Routledge, 2001.
ORGANIZATIONS
American Heart Association. 7272 Greenville Avenue, Dal-
las, TX 75231. Telephone: (800) 242-8721. Website:
<http://www.americanheart.org>.KEY TERMS
Alkaloid—An organic, compound found in plants;
chemically it is a base and usually contains at least
one nitrogen atom.
Blood-brain barrier—Aspecialized,semi-permeable
layer of cells around the blood vessels in the brain that
controls which substances can leave the circulatory
system and enter the brain.
Neurotransmitter—One of a group of chemicals
secreted by a nerve cell (neuron) to carry a chem-
ical message to another nerve cell, often as a way of
transmitting a nerve impulse. Examples of neuro-
transmitters include acetylcholine, dopamine,
serotonin, and norepinephrine.
Tolerance—Adjustment of the body to a drug
so that it takes more and more to produce the
same physiological or psychological effect, or
adjustment to a drug so that side effects are
diminished.Caffeine