Best of Naturopathy"Melatonin, Menstruation, and the Moon'

by Sari Cohen4th-year Naturopathic Medical Student - Southwest College of Naturopathic Medicine

IntroductionThe relation-

ship betweenthe moon'scycles andmenses is so

fundamental that thetwo phenomena are reiated linguistically.The terms 'moon' and 'menstruation'share the same Latin or Greek root, m-,meaning 'to measure,' Various worldreligions and cuitures haveacknowledged the bond between womenand the moon. Traditional ChineseMedicine links the moon with thefeminine, or yin principle, Jewish traditiondictates that women shouid celebrateRosh Chodesii, the new moon. Manycuitures have assigned the moon agoddess, from Babylonian Ishtar to GreekArtemis. This connection endures todaywith religious, spiritual, and even healthpractices. Herbalist Rosemary Gladstarwrites that "all the fluid energy of the earthresponds to the moon cycles" andadvises her amenorrheic patients to payattention to the lunar cycle as an adjunctto herbal therapy to regulatemenstruation.' Although it is clear that themenstrual cycle lasts more or less as longas the lunar cycle, the reason why sucha relationship should exist is not soobvious.

The pineal gland may provide onepossible connection between the lunarand menstrual cycles. The pineal glandand its main secretory hormone,metatonin, are shrouded in mystery. Theexact role of this gland has eludedscientists to this day. The ancient Greeksand later Rene Descartes, the 17thcentury French philosopher andmathematician, described the pineal as"the seat of the soul." The "third eye" ofEastern religions is associated with thepineal gland. Greenspan and Gardner, intheir textbook Basic and CiinicaiEndocrinoiogywute that "the physiologicroles of the pineal remain to beelucidated, but they involve regulation of

gonadal function and development andchronobiologic rhythms,"^

The pineal gland secretes melatoninand also contains TRH, somatostatin,GnRH, and norepinephrine, Melatonin,also called N-Acetyi-5-methoxy-tryptamine, is a derivative of tryptophan.The pineal releases melatonin intocerebrospinal fluid and into generalcirculation. Melatonin secretion increasesin response to darkness andhypoglycemia. This primarily nocturnalhormone is well known for its sleep-inducing abilities and its role in thecircadian rhythm, Murray and Pizzornoreport that it also possesses antioxidanteffects,^ Other important functions includeanti-tumor and anti-aging activity.

Less understood is melatonin's role inreproductive function, namely its actionson the menstrual cycle. This paper willexplore the intricate relationship betweenmelatonin, the female sex hormones,prolactin, and the lunar cycle. We knowthat the menstrual cycle and lunar cyclecoincide and that the pineal gland Issensitive to light exposure and is relatedto gonadal function. Are these processeslinked in some way? In a preliminarysearch of scientific literature for researchand articles on the pineal gland,melatonin, menstruation, and lunarcycles, a number of intriguing factssurface. Analysis of this data leads me topropose that the moon influences themenstrual cycle through (possiblyvestigial) interactions between lunar lightexposure and melatonin release. Thesepropositions are not explicitly proven instudies due to the lack of research in thisarea. The aim of this paper is simply topoint out the potential implications ofvarious research studies, combiningphysiology, folk wisdom, and commonsense to explain and explore the moon'seffects on the menstrual cycle,

Melatonin and MensesThere is a direct correlation between

melatonin and the menstrual cycle. Three

studies report that melatonin reaches itszenith during menstruation and its nadirduring ovulation.* Research by Cagnacciet al, found that melatonin enhances LHin the luteal phase and acts withprogesterone to attenuate the core bodytemperature.^ In their paper "Melatoninand its role in human reproduction,"Wojtowicz and Jakie! state that melatoninis likely essential in both folliculogenesisand spermatogenesis.^ Melatonin mayaffect the female hormones and therebyhelp regulate the menstrual cycle via itsrelationship with prolactin. The nightlymelatonin surge is followed by a surge inprolactin.^ Prolactin is one of sixhormones secreted by the anteriorpituitary, Prolactin stimulates lactation inpostpartum women and breastdevelopment in pregnant women, butotherwise its role in physiologic gonadalfunction is unclear. The pathological stateof hyperprolactinemia is associated withsuppressed gonadal function:anovulation, amenorrhea, and infertility.Prolactin appears to decrease thepulsatile secretion of FSH and LH withoutaffecting these hormones' basal levels.Prolactin also suppresses the midcyclesurge of LH.^ This suppression wouldeffectively inhibit ovulation. In oneJapanese study by Miyauchi et al,,women in the foilicular phase of theircycles were exposed to light duringvarious hours of the night and their serumlevels of melatonin, prolactin, FSH, andLH were then measured. Melatonin andprolactin were decreased while FSHlevels increased,^ These levels mirror thefindings mentioned previously, thatmelatonin is higher in the foilicular phaseand decreased in the luteal phase of themenstrual cycle. The role of melatonin inthe menstrual cycle may therefore be anindirect one: melatonin is linked withprolactin release, which then acts onfemale sex hormones.

Although the mechanism of action isunclear, melatonin's modulatory effectson the reproductive cycle is undisputed.

94 TOWNSEND LETTER for DOCTORS & PATIENTS - FEBRUARY/MARCH 2005

Using melatonin combined withprogesterone as a contraceptive agent(Beta Oval) has been explored for over adecade.10 Puberty and menopause arealso associated with a dramatic reductionin melatonin levels, though again, themechanism and significance of thiscorrelation are as yet undetermined."

The regulation of the reproductivecycle by melatonin has been studied inboth animals and humans and appearsto allow for photoperiodic control ofreproduction. Seasonal fertility in animalsallows for optimal food availability andclimate to ensure survival of offspring.The continuous ovulation currently seenin humans is the exception rather thanthe rule among mammals,Photoperiodicity of fertility in humans isthought to be largely an evolutionary relic.In their paper "Hypotheses: melatonin/steroid combination contraceptives willprevent breast cancer," Cohen et al. notethat the evolutionary period during whichfemale humans began continuousovulatory cycles coincides with thephylogenetic point at which womenbecame sensitive to breast cancer. Themore ovulatory cycles experienced by awoman, the greater the stimulation ofbreast tissue and therefore, the greaterthe risk of breast cell proliferation. Theypropose that a "melatonin/ovarian-steroidcontraceptive will restore the lostmechanism of endogenous anovulation,"thereby reducing the continuousproliferation of epithelial breast cells.'^

Investigation shows that whileseasonal fertility in humans is notaccepted as the dominant paradigm, atleast one group of women does exhibitphotoperiodicity in their reproductivecycles, A study in Finland by Kivela et al,examined the seasonal variations ofmelatonin, prolactin, FSH and LH inwomen. The authors discovered thatnighttime melatonin levels were higher inwinter than in summer, and that mid-cycleLH levels were higher in summer than inwinter. They concluded that, "it is possiblethat in winter the high levels of melatoninin the foilicular phase have an inhibitoryeffect on the serum LH levels. In summerthe melatonin levels are lower andperhaps less inhibitory on the secretionof LH, resulting in the stimulation of thereproductive competence in humanfemales."'^ The higher level of melatoninsecretion in the winter is due to thedecreased light exposure in the wintermonths in Scandinavia, during which timethe average daylight is 5 hours, comparedto 22 hours in the summer. In another

Melatonin, Menstruation, and the Moon

study considering seasonal variations inhuman reproduction, Wojtowicz andJakiel also report an increase in thenumber of irregular anovulatory cycles inwinter compared to summer.'*

Melatonin and the MoonIf pineal activity and melatonin

secretion is affected by seasonal lightchanges, it stands to reason that lunarlight changes may also exert an effect onthis gland. Scientific literature addressingthe relationship between lunar cycles andmelatonin is sparse. One paper by Law,"The Study of Menstrual Cycle and itsRelationship to the Moon," noted that themajority of subjects menstruated at thenew moon, with a correlation betweenmelatonin levels and moon phase.However, these researchers onlymeasured melatonin levels in a fewsubjects, not the entire cohort. Anotherstudy examining melatonin secretion inbirds concluded that secretion of thishormone was highest at the new moonand lowest during the full moon,'^ Sincemelatonin release is stimulated bydarkness, it is not surprising that zenithmelatonin levels were recorded during thedark phase of the moon. The logicalconclusion is that melatonin could bemodulated not only by diurnal andseasonal variations In light, but also bymonthly variations in lunar illumination inplaces where lunar light is still markedlyvisible. More research on the effects ofmoonlight on melatonin in humans isclearly necessary to further the ideaspresented in this section.

Menstrual cycle and Lunar cycleThe lunar cycle influences

reproductive activity of several species.In her fascinating book Lunaception,Louise Lacey cites numerous researcharticles on the moon's effects onreproduction. She found many studiesthat demonstrated lunar periodicity in thereproductive cycles of sea scallops,grunions, sea worms, mussels, somealgae, insects, rodents, lemurs, andlorisoids. Many cross-cultural sourcesassociate the new moon withmenstruation and the full moon withovulation in humans. For example,herbalist Susun S. Weed, whose work isinformed by ancient goddess-centeredspirituality, writes in her book MenopausaiYears about the woman "moved topassionate sex when the moon was full

and her egg was ripe,"'^ She also guideswomen with cessation of menses torenew their menstrual cycle withemmenagogue herbs given "for the threedays of the new moon, to stimulatemenstrual bleeding and restore normalcycling."" The Native American Lakotatradition reinforces this, teaching thatwhen Grandmother Moon covers her face(i.e., the new moon), women go into aquiet, dark place and bleed. This topic isexplored by current religious andwomen's groups embracing goddess-centered spirituality, as well as by feministgroups trying to rekindle the elevation ofmenstruation to more than anembarrassing inconvenience,'^

Research studies conflict, however,regarding modern trends of womenmenstruating with the new moon andovulating with the full moon. In supportof this theory is a study by Criss andMarcum suggesting that "the period ofdecreasing illumination immediately afterfull moon may precipitate ovulation."'^Another study looking at effects of lighton the menstrual cycle concluded thatphotic influences stimulate ovulation.^°However, in a few other studies, themajority of women bled in the light phaseand ovulated in the dark phase of themoon.^^ Perhaps this discrepancy wouldbe rectified in areas with less artificial lightand light pollution.

Despite modern science's inability toprovide corroborating evidence, amplecultural and historical referencesassociate ovulation with the full moon.Perhaps it is not surprising that womenmay tend to sleep less at this time of themonth. In a Japanese study, researchersnoted that time in bed and time asleepincreased in the menstrual and foilicularphases, while women were more likelyto be awake in the early luteal phase.Although these results were notstatistically significant, the authorsconcluded, "It is possible that themenstrual cycle [affects] the plasmamelatonin level and sleep-wakerhythm,"^^ If our ultimate biological aim isthe propagation of the species, surely weshould be more awake and active (andtherefore more likely to engage in sexualactivity) during the times when conceptionis most likely. In fact, several studies haveexamined how frequency of sexualactivity varies with the menstrual cycle.Many women report heightened sexual

TOWNSEND LETTER tor DOCTORS « PATIENTS - FEBRUARY/MARCH 2005 95

Melatonin, Menstruation, and the Moon

desire at both menstruation and atovulation, but sexual activity increases atovulation. ̂ ^

SummaryIn this paper I have attempted to clarify

the connection between melatonin, thelunar cycle, and the menstrual cycle,theorizing that the basis of lunar 'control'of the menstrual cycle is due to lunar lighteffects on melatonin secretion. Scienceprovides ample evidence that the pinealgland exerts neuroendocrine effects onhuman reproductive activity via prolactinand melatonin. Additionally, melatonin isrelated to light exposure and seasonalchanges. Melatonin's relationship with thelunar cycle is less well established.Melatonin, which is suppressive togonadal function, seems to have itshighest secretion during the new moon.Many women tend to menstnjate with thenew moon and sleep more during thistime as well. The converse is true at thefull moon: melatonin secretion is low,gonadal function is intact, ovulationoccurs more frequently, and steep isdecreased. These factors all serve toincrease the likelihood of conception.

This model describes the way that thefemale body would function in a world withfewer external factors to confound naturalbiorhythms. Perhaps the strictly biologicalcontrol of our menstrual cycies has beenusurped by the effects of exogenoushormones (HRT, birth control pills,xenoestrogens in plastics and pesticides,hormones in meat and dairy) and themitigating influence of light pollution onthe pineal gland. For instance, oralcontraceptives have been proven to alterthe circadian rhythm of melatonin andreduce women's sensitivity to light.̂ " Also,working the night shift (i.e., nocturnalexposure to artificial light) suppressesovarian function by altering the circadianrhythm of prolactin and melatonin, leadingto irregular menses in women working atnight." These are just two examples ofthe derangement of natural cycles byexternal influences, which are likely tohave profound effects on fertility,longevity, and general health.

With scant scientific evidence tocorroborate our biological legacy andvastly different environmental conditionscompared to even 30 years ago, onemight wonder why we should bother toexamine the interactions between themoon and hormonal cycles. The

spectrum of menstrual disorders,infertility, and female reproductivecancers prevalent in the industrial worldmay very likely be related to thewidespread interruption of naturalbiological rhythms, including therelationship between the lunar cycle andthe menstrual cycle. The link betweenmelatonin and breast cancer may be dueto the mitigating effects of light pollutionon melatonin release. This theory hasbeen investigated for years and thedebate remains unsettled. Stevens andRea summarize the theory as follows:"...if electric lighting as currentlyemployed contributes to 'circadiandisruption' it may be an important causeof 'endocrine disruption' and therebycontribute to a high risk of breast cancerin industrialized societies."^ Giickman etal. note that this theory of light pollutionhaving a causal relationship with breastcancer is supported by epidemiologicatdata showing that blind women havedecreased rates of breast cancer, andthat female night-shift workers havehigher rates of breast cancer." Theseauthors point to the need for lightingstrategies to take into accountneuroendocrine rhythms and not simplyvisual performance requirements.Besides direct endocrine disruption,decreased melatonin levels may affectcancer because melatonin possessesoncostatic activity. Schernhammer andSchulmeister propose that loweredmelatonin levels due to nocturnal lightexposure enhance general tumordevelopment because melatonin iscancer-protective.^' Allocating moreresources to studying the evolution of ourreproductive cycle and our biologicallegacy may address some of the gravehealth concerns affecting women, andtherefore, the health of the human race.The entire medical community should beaware of the links between infertility,hormonal cancers, and environmentalconcerns such as iight, air, and waterpollution.

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