Suicide and lunar cycles: a critical review over 28 years

The last jump: epidemiology of suicides at the Tour Eiffel (Paris) between 1950 and 1989

The Eiffel Tower (Paris, France) has been attracting many candidates for suicide over the years. The aim of this study was to determine the patterns of people who committed suicide by jumping. Permission to access the unpublished records of the Paris Police Prefecture made it possible to compile press articles related to suicides from April 1950 to March 1989. 155 articles corresponding to 79 cases were kept for analysis. There were significantly more males (66%), as compared with an expected theoretical distribution of 1/2 for each sex (p = 0.002). Median age was 38.0 years old. Suicide peak was reached during the months of August and October (13% for each), while February was poor in suicides (3%). Tuesdays and Saturdays were the more impacted days. Hourly suicide rates were 8% (morning), 11% (noon), 7% (afternoon), and 5% (evening-night). Moon phases did not correlate with suicide occurrence. The main context described was that of a psychiatric pathology (49%). Death occurred in 92% of the reported cases. Sex ratio, ages, decrease during the cold season, no association with moon phases, and underlying psychiatric pathologies were consistent with trends for either all-cause suicides or suicide jumps from a platform. Conversely, unusual trough in suicides on Mondays and noon peak in suicide rate have been, respectively, attributed to small sample size and closure at night. As jumping corresponds to both ease and proximity, we believe the implementation of protective measures in the early 1960s succeeded in reducing the number of suicides overall.

Don't Blame It on the Moon

Aim: There is a longstanding, popular belief that the lunar cycle has an impact on human behavior. The purpose of this study was to evaluate changes in behavior amongst psychiatric patients at a mental health facility over a 7-year period in comparison to the lunar cycle. Method: A retrospective analysis was conducted using behavioral occurrence reports from a hospital database for a 252-bed adult psychiatric hospital in Canada. There were 7,153 behavioral occurrences during the study period across 627,763 patient days. Results: Occurrences varied greatly by lunar day, with peaks above the average for some days and dips below for others, while maintaining the average for the rest of the lunar days; however, no specific pattern was observed and the variation was not statistically significant. The popular notion that a full moon arouses behavioral disturbances was not supported in this analysis of psychiatric inpatients. Clinical Implications: The belief that the full moon causes escalating behaviors should be critically evaluated by healthcare providers as it may contribute to further stigmatization of individuals with mental illness.

Increased suicide risk among younger women in winter during full moon in northern Europe. An artifact or a novel finding?

Available evidence suggests that there is no effect of moon phases on suicidal behavior. However, a Finnish study recently reported elevated suicide rates during full-moon, but only among premenopausal women and only in winter. This could not be replicated in an Austrian study and stirred a discussion about whether the Finnish finding was false-positive or if there are unaccounted moderator variables differing between Finland and Austria. The goal of the present study was to provide another replication with data from Sweden, which is geographically more comparable to Finland than Austria. We also investigated the discussed moderator variables latitude and nightly artificial brightness. There were 48,537 suicides available for analysis. The fraction of suicides during the full-moon quarter in winter did not differ significantly from the expected 25% among premenopausal women (23.3%) and in the full sample (24.7%). The incidence risk ratios for full moon quarter in Poisson regression models were 0.96 (95% CI: 0.90-1.02) for premenopausal women and 1.01 (95% CI: 0.99-1.04) for the full sample. According to Bayes-factor analysis, the evidence supports the null-hypothesis (no association) over the alternative hypothesis (some association). We found similar results when we split the data by latitude and artificial nightly brightness, respectively. In line with the Austrian study, there was no increase of suicides in Sweden among premenopausal women in winter during full-moon. The results from the Finnish study are likely false positive, perhaps resulting from problematic but common research and publication practices, which we discuss.

Synodic lunar phases and suicide: based on 2605 suicides over 23 years, a full moon peak is apparent in premenopausal women from northern Finland

Suicide data for this study were available for the period of March 1988 to June 2011, and involved 2111 male and 494 female victims from the Finnish province of Oulu. Data for lunar phases during that period were categorised into three groups: new moon (<25% visible), full moon (>75% visible) and other times with values in between. Seasonal effects were controlled with definitions for winter (Nov, Dec, Jan), spring (Feb, Mar, Apr), summer (May, June, July), and autumn (Aug, Sep, Oct). Suicide occurrences during different lunar phases were compared with their expected distribution using multinomial tests with all tests being two-tailed. Statistical significance was set at p < 0.05. No correlation between suicides and moon phase in any of the four seasons was apparent for male victims, but in winter for women it was (p = 0.001). Further analysis of the data revealed that the full moon association was statistically significant only for premenopausal women, defined as female victims younger than 45 years of age. To explain this unexpected finding a number of factors were considered, e.g., the darkness of a northern Finnish winter with increases of SAD and depression especially in premenopausal women, the influence of the lunar periodicity on the menstrual cycle, and cosmogeophysical effects on the humoral and autonomous nervous system.

Lunar cycle in homicides: a population-based time series study in Finland

OBJECTIVE

To test whether homicides in Finland vary according to moon phases.

DESIGN

A time series study.

SETTING

Finland.

PARTICIPANTS

6808 homicides committed in 1961-2014.

OUTCOME

Daily numbers of homicides.

METHOD

The daily numbers of homicides were related to eight moon phases and the illuminated percentage of the moon disc using negative binomial regression. To identify lunar patterns, piecewise linear terms of lunar days were used, together with changes from one moon phase to another. Homicides were similarly regressed on quintiles of the illuminated percentage of the moon disc. A periodic term of length 29.53 days was included to detect cyclic patterns. The results were adjusted for sex, age, secular trend, distance from the moon, seasons, weekday, major holidays and temperature.

RESULTS

During the full moon, 15% less homicides were committed than during the new moon (RR 0.85; 95% CI 0.77 to 0.94) and 86% less during the lightest quintile of illumination compared with the darkest quintile (RR 0.14; 95% CI 0.04 to 0.50). Adjustments did not change the results. Piecewise linear regressions showed a significant decline in homicides at the full moon and a rise thereafter. The full moon drop in homicides was directionally similar for seasons, weekdays, sex, age and time periods, and it was particularly pronounced in the early part of period studied (1961-1974). Periodic regression showed a regular cyclic pattern of length 29.53 days (p~0.035).

CONCLUSIONS

Contrary to current scientific opinion, an association exists between moon phases and homicides, and contrary to what has been previously assumed, homicides declined during the full moon, especially in earlier decades. However, the causality of the association remains elusive.

Moon/sun - suicide

INTRODUCTION

Findings concerning the effects of moon phases and sun activity on suicide are mixed in the international literature.

AIM

Our aim was to examine the hypothesised effects according to gender and age on Hungarian data covering more than 30 years.

METHODS

Time series ARIMA models and dynamic regression models were applied in our analysis.

RESULTS

Among women aged 20-49 years, a significant increase in the risk of suicide has been observed during proton solar events. At the same time, among women aged 50-59 years a slight but significant decrease has been identified in the risk of suicide during magnetic storms and full moons.

CONCLUSION

Proton solar events, geomagnetic storms and moon phases caused changes in the risk of suicide in certain age groups in the case of women only.

No evidence of purported lunar effect on hospital admission rates or birth rates

Background

Studies indicate that a fraction of nursing professionals believe in a “lunar effect”—a purported correlation between the phases of the Earth’s moon and human affairs, such as birth rates, blood loss, or fertility.

Purpose

This article addresses some of the methodological errors and cognitive biases that can explain the human tendency of perceiving a lunar effect where there is none.

Approach

This article reviews basic standards of evidence and, using an example from the published literature, illustrates how disregarding these standards can lead to erroneous conclusions.

Findings

Román, Soriano, Fuentes, Gálvez, and Fernández (2004) suggested that the number of hospital admissions related to gastrointestinal bleeding was somehow influenced by the phases of the Earth’s moon. Specifically, the authors claimed that the rate of hospital admissions to their bleeding unit is higher during the full moon than at other times. Their report contains a number of methodological and statistical flaws that invalidate their conclusions. Reanalysis of their data with proper procedures shows no evidence that the full moon influences the rate of hospital admissions, a result that is consistent with numerous peer-reviewed studies and meta-analyses. A review of the literature shows that birth rates are also uncorrelated to lunar phases.

Conclusions

Data collection and analysis shortcomings, as well as powerful cognitive biases, can lead to erroneous conclusions about the purported lunar effect on human affairs. Adherence to basic standards of evidence can help assess the validity of questionable beliefs.

Pediatric psychiatric emergency department visits during a full moon

OBJECTIVE

This study aimed to verify the hypothesis that the lunar cycle influences the number of pediatric psychiatric emergency department (ED) visits.

METHODS

Pediatric psychiatric ED visits between 2009 and 2011 were obtained retrospectively. Patients aged between 4 and 21 years presenting to Miami Children's Hospital ED with a primary psychiatric complaint were included in the study. Patients with a concomitant psychiatric problem and a secondary medical condition were excluded. The number of psychiatric visits was retrieved for the full moon dates, control dates as well as the day before and after the full moon when the moon appears full to the naked eye (full moon effect). A comparison was made using the 2-sample independent t test.

RESULTS

Between 2009 and 2011, 36 dates were considered as the true full moon dates and 108 dates as the "full moon effect." A total of 559 patients were included in the study. The 2-sample independent t tests were performed between the actual full moon date and control dates, as well as between the "full moon effect" dates and control dates. Our results failed to show a statistical significance when comparing the number of pediatric psychiatric patients presenting to a children's hospital ED during a full moon and a non-full moon date.

CONCLUSIONS

Our study's results are in agreement with those involving adult patients. The full moon does not affect psychiatric visits in a children's hospital.

A study on the physical fitness index, heart rate and blood pressure in different phases of lunar month on male human subjects

The gravitational pull of the moon on the earth is not the same in all phases of the lunar month, i.e. new moon (NM), first quarter (FQ), full moon (FM) and third quarter (TQ), and as a result the amplitude of tide differs in different phases. The gravitational pull of the moon may have effects on the fluid compartments of the human body and hence the cardiovascular system may be affected differentially in the different phases of the lunar month. In the present study resting heart rate (HR) and blood pressure (BP), physical fitness index (PFI), peak HR and BP immediately after step test, and recovery HR and BP after step test were measured during different phases of the lunar month in 76 male university students (age 23.7 ± 1.7 years). At rest, both systolic and mean arterial BP were ∼5 mmHg lower in NM and FM compared to FQ and TQ, but resting HR was not significantly different between phases. Further, peak HR and peak systolic BP after step test were lower (∼4 beat/min and ∼5 mmHg, respectively) in NM and FM compared to FQ and TQ. PFI was also higher (∼5) in NM and FM compared to FQ and TQ. Recovery of HR after step test was quicker in NM and FM compared to that of FQ and TQ. It appears from this study that gravitational pull of the moon may affect the cardiovascular functions of the human body. Moreover, the physical efficiency of humans is increased in NM and FM due to these altered cardiovascular regulations.

Influence of Lunar Phases on Suicide: The End of a Myth? A Population‐Based Study

The hypothesis of lunar influence on suicide remains widespread, despite the fact that little scientific evidence to substantiate it. We conducted a population-based study to assess the influence of the lunar phases on suicides according to age, sex, and chosen method. The study included all suicides in Middle Franconia between 1998 and 2003. From a population-based sample of 3351 events, the files of 3054 suicides (1949 males and 1105 females) were complete for the study variables. Data were categorized by lunar phase, sex, age, and chosen method-"violent" vs. "non-violent" acts. No significant relationship was detected between the full, absent, and moon's interphases and suicide incidence. Nevertheless, there was a weak association between the absent moon and choice of a non-violent suicide method in men aged less than the median of 40.2 yrs. There was no evidence of a relationship between suicide and lunar phase. Some explanations for this phenomenon are discussed.

Human responses to the geophysical daily, annual and lunar cycles

Collectively the daily, seasonal, lunar and tidal geophysical cycles regulate much of the temporal biology of life on Earth. The increasing isolation of human societies from these geophysical cycles, as a result of improved living conditions, high-quality nutrition and 24/7 working practices, have led many to believe that human biology functions independently of them. Yet recent studies have highlighted the dominant role that our circadian clock plays in the organisation of 24 hour patterns of behaviour and physiology. Preferred wake and sleep times are to a large extent driven by an endogenous temporal program that uses sunlight as an entraining cue. The alarm clock can drive human activity rhythms but has little direct effect on our endogenous 24 hour physiology. In many situations, our biology and our society appear to be in serious opposition, and the damaging consequences to our health under these circumstances are increasingly recognised. The seasons dominate the lives of non-equatorial species, and until recently, they also had a marked influence on much of human biology. Despite human isolation from seasonal changes in temperature, food and photoperiod in the industrialised nations, the seasons still appear to have a small, but significant, impact upon when individuals are born and many aspects of health. The seasonal changes that modulate our biology, and how these factors might interact with the social and metabolic status of the individual to drive seasonal effects, are still poorly understood. Lunar cycles had, and continue to have, an influence upon human culture, though despite a persistent belief that our mental health and other behaviours are modulated by the phase of the moon, there is no solid evidence that human biology is in any way regulated by the lunar cycle.

Admission to intensive care for parasuicide by self-poisoning: variation by time cycles, climate and the lunar cycle

The aim of this study was to characterize patients after self-poisoning with suicidal intent regarding age, sex and type of substances ingested, as well as to identify temporal variations of attempted suicides and associations with climate variables and the lunar cycle. During the years 2002-2004, a total of 691 patients were admitted for self-poisoning parasuicides. The male to female ratio was 1:1.65 with mean ages of 39 and 37 years, respectively. Benzodiazepines and antidepressants were the most frequently taken substances. A significant variation with the time of the day with a peak before midnight was observed for both sexes. Variation with the day of the week was less clear and showed a peak incidence for parasuicides on Mondays. There was no significant variation with the monthly or annual cycle. The frequency of parasuicides was associated with "bad weather" (precipitation). No association of parasuicide incidences to the lunar cycle was observed.

Lunar phases and zodiac signs do not influence quality of radical cystectomy--a statistical analysis of 452 patients with invasive bladder cancer

OBJECTIVE

To determine the influence of the lunar phases and the position of the moon in the zodiac on the frequency of complications and the survival of bladder cancer patients after radical cystectomy. It has been postulated that radical cystectomy performed during the waxing moon, or particularly at full moon, or at the zodiac sign Libra is associated with a poorer outcome.

MATERIAL AND METHODS

We tested this hypothesis by evaluating the progression-free survival, the complication rate and the re-operation rate for 452 consecutive patients after radical cystectomy. In this retrospective review, the dates of surgery were allocated to the lunar phases and the zodiac signs. Based on these classifications, the patients were placed in groups which combined the lunar phase laws and differentiated between evidently unfavorable (full moon or waxing moon and/or the zodiac sign Libra; assigned to group 1) and favorable periods for surgery (new moon or waning moon and other signs of the zodiac apart from Libra; assigned to group 2). The mean follow-up was 49 months (range 0-158 months).

RESULTS

A total of 244 patients (54%) were operated during an unfavorable period (group 1) and 208 (46%) patients during the auspicious period (group 2). The mean age, gender and kind of urinary derivation did not differ significantly in the two groups. Pathological tumor stages were evenly distributed according to the lunar phase groups (P = 0.713). We found no significant differences in the perioperative mortality rates, early re-operation rates, early complications, and late complications across the two groups. No significant differences in progression-free survival were observed when timing of cystectomy during the lunar cycle was considered (P = 0.231).

CONCLUSIONS

Our analysis demonstrated no predictable influence of the lunar phase on survival or complications. Although this was not a prospective randomized trial, the statistical magnitude of the results do not support any recommendations for scheduling patients for radical cystectomy at any particular day of the lunar phase.

Are patient falls in the hospital associated with lunar cycles? A retrospective observational study

BACKGROUND

Falls and associated negative outcomes in hospitalized patients are of significant concerns. The etiology of hospital inpatient falls is multifactorial, including both intrinsic and extrinsic factors. Anecdotes from clinical practice exist in which health care professionals express the idea that the number of patient falls increases during times of full moon. The aim of this study was to examine in-hospital patient fall rates and their associations with days of the week, months, seasons and lunar cycles.

METHODS

3,842 fall incident reports of adult in-patients who fell while hospitalized in a 300-bed urban public hospital in Zurich, Switzerland were included. Adjusted fall rates per 1'000 patient days were compared with days of the week, months, and 62 complete lunar cycles from 1999 to 2003.

RESULTS

The fall rate per 1000 patient days fluctuated slightly over the entire observation time, ranging from 8.4 falls to 9.7 falls per month (P = 0.757), and from 8.3 falls on Mondays to 9.3 falls on Saturdays (P = 0.587). The fall rate per 1000 patient days within the lunar days ranged from 7.2 falls on lunar day 17 to 10.6 falls on lunar day 20 (P = 0.575).

CONCLUSION

The inpatient fall rates in this hospital were neither associated with days of the week, months, or seasons nor with lunar cycles such as full moon or new moon. Preventive strategies should be focused on patients' modifiable fall risk factors and the provision of organizational conditions which support a safe hospital environment.

Effect of lunar cycle on temporal variation in cardiopulmonary arrest in seven emergency departments during 11 years

OBJECTIVE

To determine the effect of the phase of the full and new moon on the variation in the number of daily cardiopulmonary resuscitations.

DESIGN

A retrospective analysis of a computerized billing database of emergency department visits in a cohort of seven northern New Jersey (USA) emergency departments.

PARTICIPANTS

Consecutive patients seen by emergency department physicians over an 11-year period (1 January 1988 to 31 December 1998). We determined the timing of full and new moon days from the National Oceanographic and Aeronautic Administration website.

INTERVENTIONS

Time series regression estimated the independent effect of full and new moon days on the daily variation in cardiopulmonary resuscitations. Tests of statistical significance were made at alpha=0.05.

RESULTS

A total of 2 370 233 emergency department visits were made during the 4018-day period of study. A total of 6827 had an emergency department diagnosis of cardiopulmonary resuscitation. We found no significant difference in the occurrence of cardiopulmonary resuscitations during the full moon (P=0.97). On average there were 6.5% fewer cardiopulmonary resuscitations during new moon days (P=0.02; 95% confidence interval 1.3-11.7%).

CONCLUSION

Contrary to the traditional belief that more cardiopulmonary resuscitations occur during the full moon, we were unable to identify a significant effect during full moon days. However, there were on average 6.5% fewer cardiopulmonary resuscitations during new moon days than other days.

The moon and its relationship to oral and maxillofacial emergencies

OBJECTIVE

To study the relationship between the full moon and oral and maxillofacial emergencies.

STUDY DESIGN

Retrospective analysis of 2416 referrals to the Department of Oral and Maxillofacial Surgery, St. Bartholomews and The Royal London Hospital, London, over a 16-month period (17 lunar months). Frequency distributions were used to assess emergency workload during the week of the full moon.

RESULTS

There was a rise in referrals in the latter part of the 7-day period surrounding the full moon. There was a persistent reduction in emergency workload in the 3-day period leading up to the full moon. The results approach but do not reach significance.

CONCLUSIONS

The effect of the moon on oral and maxillofacial referrals cannot be proven.

Appointments at a thyroid outpatient clinic and the lunar cycle

INTRODUCTION

Several variables of health-related human behaviour have been analysed with regard to a possible association with lunar phases. The aim of this study was to evaluate a possible relation between the lunar cycle and the number of requests for appointments at an outpatient clinic. This variable has not been studied hitherto.

METHODS

We analysed a total number of 11,413 requests for appointments at our thyroid outpatient clinic during one year. Access to this clinic is not restricted, and all patients with known or suspected thyroid disease living in the area of Vienna may ask for an appointment. During the study period, 8,852 patients requested a follow-up appointment, and 2561 patients asked for a new appointment. We analysed a possible cyclic pattern in these requests using a nonlinear regression model based on both groups of patients.

RESULTS

A cosinus curve with a period of 29.531 days (the mean length of a lunar cycle) was significantly associated with the number of requests for both follow-up appointments (p = 0.007) and new appointments (p = 0.001). Requests for follow-up appointments had their highest peaks three days after the full moon, whereas requests for new appointments were most frequent five days afterwards.

CONCLUSION

Our findings suggest that lunar phases may affect patients' requests for appointments at a thyroid outpatient clinic. To the best of our knowledge, this is the first study reporting a possible association between health-related behaviour and lunar phases using requests for appointments as a relevant variable. There is a need for more research into the mechanism underpinning this behaviour.

Is the time of suicide a random choice? A new statistical perspective

The problem of the time distribution of suicide has aroused the interest of many authors, but their findings often appear uncertain and contradictory. These inconsistencies can be partially explained by both the choice of the sample and the statistical method used for the analysis. In this study, in order to reveal expected and unexpected periodicities in the time distribution of suicides, we analyzed a small but complete and very homogeneous sample of suicides which occurred in the Mountain District of the Metauro River Valley in Italy in the period 1960-1994. A recent circular statistics technique, the "maximization of mean vector length" was used. We found no significant weekly and lunar patterns, but significant seasonal and intraseasonal cycles, with peaks in March and at the beginning of each season. The superposition of these two significant cyclic trends was also studied.

Lunar phases and survival of breast cancer patients--a statistical analysis of 3,757 cases

The potential influence of lunar phases on human life has been widely discussed by the lay press. The purpose of this study was to find out whether the timing of surgery during particular lunar phases influences the survival of breast cancer patients. It has been postulated that breast cancer surgery performed during the waxing moon, or particularly at full moon, is associated with a poorer outcome. We tested this hypothesis by evaluating the overall survival for 3,757 consecutive patients with invasive breast cancer. All patients underwent either modified radical mastectomy or breast conserving surgery plus radiotherapy, followed by adjuvant cytotoxic or hormonal therapy. The date of definitive surgery was allocated to the lunar phases. 1,904 (50.7%) patients were operated on during the waxing moon and 1,853 (47.3%) during the waning moon. The median follow-up was 74 months (range 1-372 months). The mean age at primary surgery did not differ significantly in the two groups 58.39 (SD 13.14) versus 58.34 (12.75) (p >0.05, t-test). Breast cancer stages at initial diagnosis were evenly distributed according to the lunar phases (p = 0.325; chi-square). Survival curves were plotted according to the method of Kaplan-Meier. No significant differences were observed when timing of surgery was allocated to the lunar phases (p = 0.4841, log-rank). Subgroup analysis of premenopausal patients revealed similar results (p = 0.2950, log-rank; n = 1072). Using multivariate Cox modelling, we found a significant association between the patient's age, stage of disease and survival, whereas no association with survival was observed for the timing of surgery (RR= 1.062; 95% CI, 0.970-1.163; p = 0.1937). No significant differences in overall survival of breast cancer patients were observed when timing of breast cancer surgery during the lunar cycle was considered. Although this was not a prospective randomized trial, the statistical magnitude of the results do not support any recommendations for scheduling patients for surgery at any particular day of the lunar phase.

Declining rate of substance abuse throughout the month

PURPOSE

The timing of federal disbursements of welfare, disability, and military benefits may be associated with monthly patterns of substance abuse. We assessed whether this association was reflected in the pattern of psychiatric presentations to an emergency room.

SUBJECTS AND METHODS

We conducted a retrospective, case-control study of 12,904 patient presentations to an urban emergency department for psychiatric reasons during a 7-year period. Cases were defined as patients (n = 2,403) given a primary diagnosis of substance abuse. Controls included patients (n = 10,501) with a primary diagnosis of another psychiatric illness. We calculated the "boundary effect" (R = 100 times the number of presentations during the first week of the month divided by number of presentations during the last week of the preceding month) for each month, and averaged these values across months to determine overall effects.

RESULTS

The boundary effect was stronger for patients with primary substance abuse disorders (R = 134, 95% confidence interval [CI] = 118 to 151) than for patients with other psychiatric disorders (R = 106, 95% CI = 100 to 112; P < 0.001). Weekly presentations for substance abuse declined consistently throughout the month (P = 0.01), and declined significantly more than the incidence of other psychiatric presentations (P = 0.005). These effects remained, after adjusting for fluctuations in presentations around holidays and the new year. The lunar cycle did not influence the incidence of presentations.

CONCLUSION

Our results confirm that substance-related morbidity is highest at the beginning of the month and declines thereafter, corresponding to the availability of disposable income from monthly checks.

Gout attacks and lunar cycle

The aim was to search for periodical fluctuations in daily occurrence of gout attacks during the synodic lunar cycle. 126 gout attacks were recorded between 1972 and 1994 at known calendar dates. The synodic plexogram, displaying the number of attacks for each day of the cycle, was processed by cosinor regression. A pronounced cycling was found, with highest peaks under the new and full moon (syzygigies). Thus, the maximal occurrence of attacks coincides with the peaking lunisolar tidal effect. Similar relation of attacks to synodic moon was seen in bronchial asthma of children, and a reciprocal one in paroxysmal tachyarrhythmia. Differing pathogenetic backgrounds of these diseases substantiate the observed differences in their putative reactions on the changing cosmogeophysical environment.

Temporal variation in parasuicide among Singaporean Chinese

OBJECTIVE

The aim of this study was to determine whether there is any temporal variation in the incidence of parasuicide within the Chinese community and, if possible, to correlate the findings with prevailing cultural and social influences.

METHOD

All patients of Chinese origin referred to a teaching hospital in Singapore between 1990 and 1994 were included in the study. The cases were divided by sex and aggregated for the month and day of the week in which the parasuicides occurred.

RESULTS

Cases of parasuicide peaked on Mondays, while the lowest incidences occurred on Saturdays. The peak months were June, August and September with a trough in December and January.

CONCLUSIONS

The findings may not be amenable to any single explanation but the peak months coincided with the month of the Hungry Ghosts, which is believed to be a particularly inauspicious period, while the trough occurred during a festive period. Similarly, looking at the student population, the peaks coincided with the examination period. It appears that social and cultural factors play a significant role in the temporal variation in parasuicide in Singapore.

Suicides and the lunar cycle

The existence of lunar influence on the frequency of suicide is tested by means of a permutation test. A total of 897 suicide deaths reported by the Anatomical Forensic Institute of Madrid were analyzed by a permutation test, a direct application of Fisher's ideas. Noteworthy in this study are the testing method used and the accuracy of timing of the deaths. Both factors provide firm ground for our conclusion: there appears to be no relationship between lunar phases and suicide.

Lunar phases and psychiatric hospital admissions

To assess the lunar hypothesis as predictive of mental health emergencies and antisocial behavior, the relation of the lunar hypothesis and the occurrence of psychiatric hospital admissions of developmentally disabled adults was examined. The full moon phase of the lunar cycle did not explain a higher rate of hospital admission and accounted for only .007% of the variance. A critique of the methodology in prior research led to the suggestion that more immediate stressors and environmental factors are more plausible contributing factors to hospital admission.