meditation A method of focusing the mind for
HEALING VISUALIZATION, relaxation, stress relief, and
contemplation. Though meditation can have a
spiritual dimension for people who desire it, medi-
tation is not a religious practice. Clinical studies
show that daily meditation has the ability to
- reduce EPINEPHRINEproduction, thereby lower-
ing BLOOD PRESSUREand the frequency of ANGINA
PECTORIS - relax BLOODvessels, which also lowers blood
pressure - relax musculoskeletal structures
- instill a sense of inner calm and peacefulness
- decrease the frequency, duration, and severity
of menopausal HOT FLASHES
When meditation becomes a routine of daily
life, these effects can help lower blood pressure by
reducing the resistance blood encounters as it
flows through the arteries. They also increase the
flow of blood to muscles, helping muscle cells to
more efficiently clear lactic acid accumulations
and other metabolic wastes that cause cramping
and discomfort. Some people use meditation as a
platform to “go within” their bodies and visualize
healthy, strong cells, tissues, organs, and func-
tions. Such visualization may aid in healing during
illness or injury as well as in maintaining health.
There are many methods of meditation. Medi-
tation centers, YOGAcenters, community centers,
and health organizations often teach classes in
meditation techniques. Meditation may take place
while sitting quietly, while walking, or while
engaged in mind–body practices such as yoga and
TAI CHI. Some people chant when meditating, to
focus their meditations with specific sounds or
intents. Though a quiet location best facilitates
meditation, a person can meditate anywhere.
Many people take five-minute meditation breaks
while at work to help dissipate job stress. Children
also can learn to meditate. Meditation has no
known health risks.
See also MIND–BODY INTERACTIONS; PRAYER AND
SPIRITUALITY; STRESS AND STRESS MANAGEMENT.melatonin An endogenous (naturally occurring
within the body) HORMONEthe PINEAL GLANDpro-
duces that maintains the body’s circadian rhythms
(cycles of waking and sleeping). Melatonin may
also have ANTIOXIDANTfunctions, helping protect
cells from damage. Researchers first discovered
melatonin in the late 1950s, and early studies sug-
gested endogenous melatonin (melatonin the
body manufactures) production diminished with
increasing age. This gave rise to speculation that
melatonin played a role in the aging process. Sub-
sequent studies have been unable to substantiate
such involvement, however, and most doctors do
not believe melatonin can halt, prevent, or reverse
aging.
The daily level of melatonin in the body cycles
a pattern of peaking between 2 o’clock and 4
o’clock in the morning (which is the middle of the
night for most people) and reaching its lowest
point around midday. Researchers believe the
HYPOTHALAMUS, a structure deep within the BRAIN
that regulates vital body functions such as BREATH-
INGand BLOOD PRESSURE, receives signals from the
RETINAvia the OPTIC NERVEthat indicate whether it
is light or dark. When it is dark, the hypothalamus
signals the pineal gland to begin releasing mela-
tonin and when it is light, to stop releasing mela-
tonin. This may in part explain why people feel
drowsy when spending several hours in dark set-
tings such as movie theaters, or want to go to
sleep earlier in the winter when daylight is short
and have trouble falling asleep in summer when
daylight is much longer.88 Alternative and Complementary Approaches
Name Common Uses/Benefits Risks/Side Effects
ZEAXANTHIN prevent cataracts none known
preserve macular function and protect vision
possibly protect against LUNG CANCERand
OVARIAN CANCER