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Melatonin is a naturally occurring hormone secreted by the pineal gland, a pea-size structure at the center of the brain. As our eyes register the fall of darkness and the onset of night melatonin is produced. It signals to our body to prepare for sleep, our blood pressure dips, there is a decrease in body temperature and we start to feel sleepy. Melatonin is one of the central hormonal elements to regulating our circadian rhythms.Melatonin is often referred to as the hibernation hormone.
Melatonin & Depression
Melatonin is an important nighttime hormone associated with sleep and regeneration. However, excessive levels or daytime melatonin can cause depressive disorders. Medical research confirms the relationship between melatonin and mood disorders. The following paragraphs explain how melatonin works and why it causes depression.
Darkness & Melatonin
Melatonin is normally released by the pineal gland in the evening as sunlight is diminishing. Melatonin causes us to feel tired and withdraw. This helps us to sleep, but if we have to be awake when melatonin is in our system, we become lethargic, disoriented, irritable and moody. This explains why shift work and jet lag can be so debilitating, and why depression rates are highest in darker climates. Almost everyone with a mood disorder suffers worse in the winter because of excess melatonin in his or her system.
Daytime Melatonin
Just as with jet lag, other factors can cause our bodies to produce melatonin into the day. Some causes such as trauma, stress, injury, age or lack of light will shift your body’s timing or release of melatonin. This shift can create excessive levels during the day and not enough melatonin at night.
If you experience any of the following symptoms, you may have a melatonin imbalance:
Tiredness or lethargy during the day
Social or physical withdrawal
Irritability
Excessive sleepiness or insomnia
Specialized Light Suppresses Melatonin
The release of melatonin is triggered by photoreceptors in the eye, called melanopsin. This is how darkness signals the brain to produce melatonin and stop the production of active, daytime hormones such as serotonin. However, when stimulated by special light, these same photoreceptors also tell the brain to stop the production of melatonin.
The Role of Light in Treating Depression
Specialized bright light not only suppresses melatonin, but it is also the most effective natural way of producing serotonin and other active neurotransmitters. In December’s 2002 Lancet, researchers showed that when exposed to bright light, serotonin levels increased dramatically, while dark or cloudy days caused these levels to plummet.
More Effective than Medication
Knowing this, several researchers have found success using light to treat depression. In clinical studies, patients responded within a week to light vs. several weeks for standard antidepressants. Specialized light was non-addicting and caused none of the negative, long-term side effects of SSRI’s. However, the greatest benefit was realized when light was combined with medication. More people responded to a combination than to light or medication alone; the quality of response was greater and side effects were minimized.
Melatonin & Depression Research References
Varma A, Kaul RK, Varma P, Kalra V, Malhotra V.
The effect of antidepressants on serum melatonin levels in endogenous depression.
J Assoc Physicians India. 2002 Oct;50:1262-5.
Rohr UD, Herold J.
Melatonin deficiencies in women.
Maturitas. 2002 Apr 15;41 Suppl 1:S85-104. Review
Kripke DF, Youngstedt SD, Rex KM, Klauber MR, Elliott JA.
Melatonin excretion with affective disorders over age 60.
Psychiatry Res. 2003 May 1;118(1):47-54.
Parry BL, Sorenson DL, Meliska CJ, Basavaraj N, Zirpoli GG, Gamst A, Hauger R.
Hormonal basis of mood and postpartum disorders.
Curr Womens Health Rep. 2003 Jun;3(3):230-5.
Tuunainen A, Kripke DF, Elliott JA, Assmus JD, Rex KM, Klauber MR, Langer RD
Depression and endogenous melatonin in postmenopausal women.
J Affect Disord. 2002 May;69(1-3):149-58.
Parry BL, Newton RP.
Chronobiological basis of female-specific mood disorders.
Neuropsychopharmacology. 2001 Nov;25(5 Suppl):S102-8. Review.
Lincoln GA.
The irritable male syndrome.
Reprod Fertil Dev. 2001;13(7-8):567-76. Review.
Buijs RM, van Eden CG, Goncharuk VD, Kalsbeek A.
The biological clock tunes the organs of the body: timing by hormones and the autonomic nervous system.
J Endocrinol. 2003 Apr;177(1):17-26. Review.
Bianchi-Demicheli F, Ludicke F, Campana A.
Premenstrual dysphoric disorder: approach and treatment
Gynecol Obstet Fertil. 2003 Jan;31(1):49-54. Review. French.
Paparrigopoulos T.
Melatonin response to atenolol administration in depression: indication of beta-adrenoceptor dysfunction in a subtype of depression.
Acta Psychiatr Scand. 2002 Dec;106(6):440-5.
Loo H, Dalery J, Macher JP, Payen A.
Pilot study comparing in blind the therapeutic effect of two doses of agomelatine, melatoninergic agonist and selective 5HT2C receptors antagonist, in the treatment of major depressive disorders
Encephale. 2002 Jul-Aug;28(4):356-62.
Loo H, Hale A, D'haenen H.
Determination of the dose of agomelatine, a melatoninergic agonist and selective 5-HT(2C) antagonist, in the treatment of major depressive disorder: a placebo-controlled dose range study.
Int Clin Psychopharmacol. 2002 Sep;17(5):239-47
Fountoulakis KN, Karamouzis M, Iacovides A, Nimatoudis J, Diakogiannis J, Kaprinis G, Demitriadou A, Bech P.
Morning and evening plasma melatonin and dexamethasone suppression test in patients with nonseasonal major depressive disorder from northern Greece (latitude 40-41.5 degrees ).
Neuropsychobiology. 2001;44(3):113-7.
Rabe-Jablonska J, Szymanska A.
Diurnal profile of melatonin secretion in the acute phase of major depression and in remission.
Med Sci Monit. 2001 Sep-Oct;7(5):946-52.
Oner P, Cinar F, Kocak H, Gurdol F.
Effect of exogenous melatonin on ethanol-induced changes in Na(+),K(+)- and Ca(2+)-ATPase activities in rat synaptosomes.
Neurochem Res. 2002 Dec;27(12):1619-23.
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