Family Practice Vol. 17, No. 6, 472-474
© Oxford University Press 2000
The effect of the full moon on general practice consultation rates
Centre for Research in Primary Care, Nuffield Institute for Health, University of Leeds, 71–75 Clarendon Road, Leeds LS2 9PL, UK.
Neal RD and Colledge M. The effect of the full moon on general practice consultation rates. Family Practice 2000; 17: 472–474.
Received 26 January 2000; Accepted 17 July 2000.
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Abstract |
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 Top Abstract IntroductionSubjects, methods and resultsConclusionsReferences |
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Background. The effect of the full moon on human behaviour, the so-called ‘Transylvania hypothesis’, has fascinated the public and occupied the mind of researchers for centuries.
Objective. The aim of the present study was to determine whether or not there was any change in general practice consultation patterns around the time of the full moon.
Method. We analysed data from the fourth national morbidity study of general practice. The data set was split into two groups and analysed separately: consultations on ordinary weekdays and consultations on weekends and bank holidays. The data were split randomly into two equal sets, one for model building and one for model validation. The lunar cycle effect was assumed to be sinusoidal, on the grounds that any effect would be maximal at the time of the full moon and decline to the new moon, following a cosine curve (with a period of 29.54 days, the mean length of a lunar cycle).
Results. There was a statistically significant, but small, effect associated with the lunar cycle of 1.8% of the mean value [95% confidence interval (CI) 0.9–2.7%]. This equates to an average difference between the two extremes during the cycle of 3.6%. For this data set, this accounts for 190 (95% CI 95–285) more consultations on days at the peak of the cycle compared with those at the bottom of the cycle, or, put another way, about three consultations per practice.
Conclusion. We can speculate neither as to what the nature of these moon-related problems may be, nor as to the mechanisms underpinning such behaviour. However, we have confirmed that it does not seem to be related to anxiety and depression.
Keywords. Consultation rates, full moon, general practice.
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Introduction |
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TopAbstractIntroductionSubjects, methods and resultsConclusionsReferences |
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The effect of the full moon on human behaviour, the so-called ‘Transylvania hypothesis’, has fascinated the public and occupied the mind of researchers for centuries.1 There is a body of evidence which purports to demonstrate the effect of the full moon in relation to health and health-related behaviours, especially with regard to mental health. However, a meta-analysis, now 15 years old, has showed no consistent relationship.2 Two studies, both from single general practices, have suggested that the Transylvania hypothesis does not hold true for general practice consultations for anxiety and depression3 or for the total out-of-hours general practice workload.4 We set out to determine whether or not there was any change in general practice consultation patterns around the time of the full moon. If the hypothesis is true, there may be major implications for the organization of general practice and a need to intensify the search for the mechanism underpinning this hypothesis.
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Subjects, methods and results |
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TopAbstractIntroductionSubjects, methods and resultsConclusionsReferences |
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We analysed data from the fourth national morbidity study of general practice,5 a valid and widely used data set of 1 374 235 consultations from 60 practices. The data set was split into two groups and analysed separately: consultations on ordinary weekdays (mean of 5276 consultations per day) and consultations on weekends and bank holidays (mean of 371 consultations per day). The data were split randomly into two equal sets, one for model building and one for model validation. The number of consultations per day was transformed to a proportion of the daily mean for the year, which was used as the dependent variable. Independent variables were day of the week, month and the lunar cycle. Day of the week and month were entered into the regression model as categorical variables, with Monday and January acting as reference categories. The lunar cycle effect was assumed to be sinusoidal, on the grounds that any effect would be maximal at the time of the full moon and decline to the new moon, following a cosine curve (with a period of 29.54 days, the mean length of a lunar cycle). Therefore we considered terms of the formula:
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). The best fitting curve is shown in Figure 1.
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There was a statistically significant, but small, effect associated with the lunar cycle of 1.8% of the mean value [95% confidence interval (CI) 0.9–2.7%]. This equates to an average difference between the two extremes during the cycle of 3.6%. For this data set, this accounts for 190 (95% CI 95–285) more consultations on days at the peak of the cycle compared with those at the bottom of the cycle, or, put another way, about three consultations per practice.
Further models were examined to see if there was an effect from the moon on some specific morbidities (mental illness in general, anxiety, depression); no effect was found. We were unable to produce a meaningful model demonstrating a lunar effect for weekends and bank holidays.
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Conclusions |
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TopAbstractIntroductionSubjects, methods and resultsConclusionsReferences |
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We have demonstrated a real, if small, rise in general practice consultations 6 days after the full moon. This delay is presumably due to delays between the onset of moon-related problems and behaviours, and accessing the GP. We can speculate neither as to what the nature of these moon-related problems may be, nor as to the mechanisms underpinning such behaviour. However, we have confirmed that it does not seem to be related to anxiety and depression.3 Our findings show that the search for the cause of moon-related behaviour needs to continue; but that GPs need not make special provision for each full moon.
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Acknowledgments |
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We would like to thank Greg Cropper, whose after dinner conversation with RDN inspired this paper, and Brett Scaife for statistical advice and analysis. RDN and MC are supported through the Yorkshire Primary Care Research Network (YReN) which is funded by NHSE Northern and Yorkshire Regional Office. The views expressed here are those of the authors and not necessarily those of NHSE.
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References |
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TopAbstractIntroductionSubjects, methods and resultsConclusionsReferences |
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1 Trapp CE. Lunacy and the moon. Am J Psychiatry 1939; 94: 339–343.
2 Rotton J, Kelly IW. Much ado about the full moon: a meta-analysis of lunar-lunacy research. Psychol Bull 1985; 97: 286–306.[ISI][Medline]
3 Wilkinson G, Piccinelli M, Roberts S et al. Lunar cycle and consultations for anxiety and depression in general practice. Int J Soc Psychiatry 1997; 43: 29–34.
4 Macdonald L, Perkins P, Pickering R. Effect of the moon on general practitioners' on call work load. J Epidemiol Community Health 1994; 48: 323–326.[ISI][Medline]
5 Royal College of General Practitioners, Office of Population Censuses and Surveys, and Department of Health. Morbidity Statistics from General Practice—Fourth National Study 1991–1992. London: HMSO, 1995.
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