Special articleThe moon and madness reconsidered
Section snippets
Modern studies of lunar effects
The moon has been associated with mental disorder since antiquity, as reflected by the word ‘lunacy’ itself, which derives from Luna, the Roman goddess of the moon. Belief in the moon’s power to disorder the mind, especially by causing insanity and epilepsy when full, did not perish with the ancient world, but persisted unabated and with few challenges until well into the 19th century. In 1833 the physician Haslam in reviewing his new assignment as director of Bethlehem Royal Hospital in London
Critique of possible etiologic mechanisms for a lunar effect
What is to be made of the discrepancy between popular belief in the power of the moon and empiric evidence that no such power exists? Three general answers can be given to this question. The first is that popular wisdom is right: the moon does affect the mind, but the studies are not capturing the relevant variables. The moon may have effects we are not able to measure, or may have an effect on measured variables that is obscured by noise within the variables themselves. For example, the
The moon as a source of nocturnal illumination
Although the moon shone no brighter in antiquity than it does today, the relative importance of this light in redeeming the night for human affairs has diminished significantly in the last 200 years. It is hard for us to imagine the darkness of a moonless night, even for urbanites, before the advent of gas lighting in the beginning of the 19th century. As late as 1791, London boasted a social group known as the Lunar Society, not because its members had any particular interest in studying the
The effects of moonlight on the mind: sleep deprivation in the genesis of mania and seizures
If the full moon deprived people of sleep in the millennia before gas lighting, could this have served as a possible mechanism for the moon’s effect on the mind? Many studies in this century have shown that prolonged sleep deprivation (i.e. more than 72 h) induces cognitive changes in normal controls, especially mood symptoms and auditory and visual hallucinations Tyler, 1955, Luby et al., 1960, Ross, 1965. More germane to any possible effect of the moon, however, is more recent work
Pre-modern evidence for a specific association of the full moon with mania
The moon’s association with madness, lost now, may have been recognized over the centuries from repeated observations that susceptible people, the majority of whom we would today diagnose as bipolar, were more likely to develop manic symptoms around the full moon than at other times of the month. The 19th century French physician Esquirol (1845) anticipated the argument of this paper by recognizing that the moon’s effect on mental functioning was mediated by its light: ‘It is true that the
Possible methods for validating a sleep-deprivation theory of the moon’s effect on mental functioning
In contrast to mythological or symbolic explanations for why the moon came to be associated with madness and epilepsy, the proposal offered in the paper is potentially falsefiable and may thus be available to empirical validation. A first step would be to demonstrate that artificial lighting dampens any effects the moon may have once exerted. Indirect evidence for this comes from work by Wehr et al. (1995), showing that artificial lighting in urban environments suppresses changes in circadian
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