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What is Melatonin?
Melatonin is a hormone derived from serotonin and
produced in the pineal gland (a small, pea-sized gland located
just behind the center of your forehead) during periods of darkness,
but not light. Melatonin produces the feeling of sleepiness that
sets upon us when night falls. Exposure to light results in a
rapid breakdown of melatonin. It has been found in many well conducted
studies that melatonin can:
- reduce the latency period of the onset of sleepiness
- reduce the number of wakenings throughout the night
- correct disturbances in the circadian periodicity of the body,
often associated with air travel ("jet lag")
- melatonin can help both normal subjects and those afflicted
with various sleep pathologies
Why Sublingual? ("under the tongue")
Some substances are damaged by the strong stomach acids, and
actually break down during digestion. By dissolving in your mouth,
the sublingual melatonin is absorbed directly into your bloodstream
through the blood vessels in the tongue and cheeks. This gives
you more consistent intake -- it is not affected by digestive
enzymes, the food in your stomach, or how long it has been since
your last meal. Each time you take it, you will receive consistent
results. It is a bit more costly, but most people will take no
more than one tablet per day, so this amounts to less than two
pennies per day (about $6 per year) for a superior product!
Circadian Periodicity and How Melatonin Works
Have you ever wondered why you get sleepy at night or why sunlight
wakes you in the morning? Have you ever experienced "jet lag"?
If you have lived in a group situation, perhaps in college, with
many females in the same house, have you noticed that womens'
menstrual cycles eventually coincide in group living situations?
Have you ever wondered why mammals of a certain species all mate
at the same time of year? Well, these things aren't mere coincidences;
they are examples of circadian entrainment and disruption (in
the case of jet lag). Circadian periodicity or "rhythm" refers
to the body's daily cycle of hormone secretion. Circadian rhythms
can also be monthly, as in menstrual cycles or seasonal, as in
mammalian mating patterns. "Entrainment" refers to the organization
or ordering of a group or series of processes or patterns. Perhaps
you have had the experience of sitting outside on a warm summer
day listening to crickets chirping haphazardly for a period of
time, then almost at once their chirps coincide and they begin
to chirp in unison--the crickets' chirping became entrained. Just
like those crickets, there are hormonal functions in the body
that entrain and, when working properly, function as a clock--your
body's "internal clock" as it is often called. Melatonin is responsible
for the entrainment of many of your body's hormonal secretions.
So you can see how taking an appropriately timed dose of melatonin
can "reset" the clock in your body. This control over sleep cycles
can be quite helpful--especially to frequent air travelers.
Some Facts About Melatonin and Circadian Rhythm
There are timed secretions of hormones (think of them as biological
pendulums) that keep circadian periodicity independently of environmental
cues. These pendulums do, however, have an input pathway that
heeds environmental cues (e.g. daylength and presence of light--melatonin
secretion is stimulated by darkness and suppressed by light).
There is also an output pathway, completing a feedback cycle,
that informs your circadian periods, such as when you choose to
go to bed and how much time you spend outside. Of all outside
factors influencing the input pathway, daylength, and TIME SPENT
OUTDOORS are the most influential. The nocturnal period of melatonin
secretion is inversely proportional to daylength. Stress disrupts
the circadian rhythms of the body, as does depression.
Does Melatonin Possess Antioxidant or Anti-Aging
Properties?
When melatonin enjoyed its fifteen minutes of fame a few years
ago, popular press touted its anti-aging properties. Their argument
was fallacious on two accounts, one logical, another factual.
Factually, a gradual reduction of melatonin with aging is NOT
a universally accepted aspect of aging. At least one study we've
read revealed that healthy elderly subjects have the same melatonin
levels as young adult subjects13. (That lowered levels of melatonin
occurs in elderly popluations is possibly the result of decreased
outdoor activities.) That factual presupposition led to the logically
incorrect argument that if melatonin decreases with age, supplementing
melatonin can halt or slow the aging process. That would be like
arguing that since gasoline levels in running automobiles declines
over time, refilling the gas tank keeps the car new - absurd!
What about wear to tires, belts, hoses and filters?
There has also been talk about melatonin's antioxidant properties,
which may have some merit. Interestingly, melatonin itself possesses
very little antioxidant ability - in fact, it has been shown to
be pro-oxidant, but it may stimulate the body's own endogenous
antioxidant defense system.
How Do I Use Melatonin?
Simply take 1.5 to 3mg of melatonin approximately 30 minutes
before your desired bedtime. If you have traveled across time
zones and are adjusting to a new sleep schedule, only a day or
two of this should be needed to reset your internal clock.
Are There Any Side Effects with Melatonin?
Aside from signalling to your body that it's bedtime, melatonin
may also impart a direct soporific effect, so don't take it while
driving a vehicle or operating heavy machinery. Toxicity reports
indicate that melatonin is as safe as water, however, you should
reset your clock before you want to sleep and at no other time,
since that could negatively affect your circadian rhythms.
REFERENCES:
1. Jean-Louis G, von Gizycki H, Zizi FP. redictors
of subjective sleepiness induced by melatonin administration.
J Psychosom Res 1999 Oct;47(4):355-8.
2. Sack RL, Lewy AJ, Hughes RJ. Use of melatonin
for sleep and circadian rhythm disorders. Ann Med 1998 Feb;30(1):115-21.
3. Goldman BD. The circadian timing system and reproduction
in mammals. Steroids 1999 Sep;64(9):679-85.
4. Sakotnik A, Liebmann PM, Stoschitzky K, Lercher
P, Schauenstein K, Klein W, Eber B. Decreased melatonin synthesis
in patients with coronary artery disease. Eur Heart J 1999 Sep;20(18):1314-7.
5. Shanahan TL, Kronauer RE, Duffy JF, Williams
GH, Czeisler CA. Melatonin rhythm observed throughout a three-cycle
bright-light stimulus designed to reset the human circadian pacemaker.
J Biol Rhythms 1999 Jun;14(3):237-53.
6. Arendt J, Middleton B, Stone B, Skene D. Complex
effects of melatonin: evidence for photoperiodic responses in
humans? Sleep 1999 Aug 1;22(5):625-35.
7. Falcon J. Cellular circadian clocks in the pineal.
Prog Neurobiol 1999 Jun;58(2):121-62.
8. Amir S, Stewart J. The effectiveness of light
on the circadian clock is linked to its emotional value. Neuroscience
1999 Jan;88(2):339-45.
9. Best JD, Maywood ES, Smith KL, Hastings MH. Rapid
resetting of the mammalian circadian clock. J Neurosci 1999 Jan
15;19(2):828-35.
10. Helfrich-Forster C, Stengl M, Homberg U. Organization
of the circadian system in insects. Chronobiol Int 1998 Nov;15(6):567-94.
11. Bunnell DE, Treiber SP, Phillips NH, Berger
RJ. Effects of evening bright light exposure on melatonin, body
temperature and sleep. J Sleep Res 1992 Mar;1(1):17-23
12. Medina-Navarro R, Duran-Reyes G, Hicks JJ. Pro-oxidating
properties of melatonin in the in vitro interaction with the singlet
oxygen. Endocr Res 1999 Aug-Nov;25(3-4):263-80.
13. Zeitzer JM, Daniels JE, Duffy JF, Klerman EB,
Shanahan TL, Dijk DJ, Czeisler CA. Do plasma melatonin concentrations
decline with age? Am J Med 1999 Nov;107(5):432-6
14. Czeisler CA, Klerman EB. Circadian and sleep-dependent
regulation of hormone release in humans. Recent Prog Horm Res
1999;54:97-130; discussion 130-2.
15. Gillette MU, Tischkau SA. Suprachiasmatic nucleus:
the brain's circadian clock. Recent Prog Horm Res 1999;54:33-58;
discussion 58-9.
16. Benot S, Goberna R, Reiter RJ, Garcia-Maurino
S, Osuna C, Guerrero JM. Physiological levels of melatonin contribute
to the antioxidant capacity of human serum. J Pineal Res 1999
Aug;27(1):59-64.
17. Vermeulen A.[Juvenile hormones, reality or myth]?[Article
in Dutch]. Verh K Acad Geneeskd Belg 1997;59(1):19-33.
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