Have you ever found it difficult to sleep under the bright light of a full moon? For ages, many have believed that the Moon has the ability to cause sleepless nights and unusual behavior, even leading to madness. The term “lunacy” directly derives from the Latin word “luna,” meaning Moon.
Various professionals, including police officers and hospital staff, often claim that their workloads increase during full moons. However, does scientific evidence support these beliefs? The reality is more complex than folklore would suggest. Research indicates that the full moon can have a modest impact on sleep, while its effects on mental health remain uncertain.
As a neurologist specializing in sleep medicine, I am intrigued by how ancient myths regarding moonlight and madness may relate to something far more common: our restless nights under moonlit skies.
Effects of the Full Moon on Sleep
Multiple studies confirm that sleep patterns change in the days leading up to a full moon, when moonlight is at its brightest. During this phase, individuals tend to sleep approximately 20 minutes less, take longer to fall asleep, and experience reduced time in deep, restorative sleep. Large-scale studies across different cultures also reveal that people tend to go to bed later and sleep for shorter durations in the nights preceding a full moon.
The primary reason for these changes is the increased light exposure. A bright moon in the evening can disrupt the body”s internal clock, lower melatonin levels— the hormone that signals sleep—and keep the mind more alert. Although the impact is generally modest, with most individuals losing about 15 to 30 minutes of sleep, it is significant enough to be measurable. This effect is particularly pronounced in areas with limited artificial light, like rural settings or during camping trips. Interestingly, research suggests that men and women may experience these changes differently. Men tend to lose more sleep in the waxing phase, while women might experience slightly less deep sleep around the full moon.
Connection to Mental Health
Historically, the full moon has been blamed for inciting madness. Folklore has suggested that its brightness could trigger mania in individuals with bipolar disorder, provoke seizures in those with epilepsy, or lead to psychotic episodes in individuals with schizophrenia. The rationale was straightforward: sleep deprivation caused by a bright moon could unravel vulnerable minds.
Contemporary research offers a different perspective. It is well-established that sleep deprivation is a significant contributor to mental health issues. Even a single poor night”s sleep can increase anxiety and decrease mood. Chronic sleep disruption heightens the risk of depression, suicidal thoughts, and exacerbation of disorders such as bipolar disorder and schizophrenia. This implies that even minimal sleep loss associated with a full moon could have more profound implications for those already at risk. For example, someone with bipolar disorder might be particularly sensitive to reduced or fragmented sleep compared to others.
However, when researchers analyze larger populations, evidence linking lunar phases to psychiatric crises is weak. No consistent patterns have emerged regarding the moon”s influence on hospital admissions, discharges, or length of stays. Some studies have suggested minor effects, such as increased restraint use in psychiatric hospitals in India during full moons and a slight rise in schizophrenia admissions in China correlating with full moons, but these findings are not universally applicable and may reflect local cultural practices or hospital protocols rather than biological effects.
Ultimately, while the full moon may slightly reduce sleep duration, the impact on mental health is complex, particularly for those with conditions like depression, bipolar disorder, schizophrenia, or epilepsy, as well as adolescents who may be more susceptible to sleep disruptions. Nevertheless, the notion that the full moon directly causes significant psychiatric disturbances remains largely a myth.
Debunking Other Lunar Theories
Over the years, scientists have investigated various explanations for the perceived effects of the moon, including gravitational “tidal” forces on the body, subtle geomagnetic shifts, and variations in barometric pressure. However, none of these theories have stood up to rigorous scrutiny. The gravitational forces responsible for ocean tides are far too weak to have any effect on human physiology, and studies examining geomagnetic and atmospheric changes during lunar phases have produced inconsistent results. Therefore, sleep disruption due to nighttime light exposure remains the most credible connection between the Moon and human behavior.
Why the Myth Persists
If the scientific evidence is inconclusive, why do so many people still believe in the “full moon effect”? Psychologists attribute this to a phenomenon known as illusory correlation. People tend to remember unusual occurrences that coincide with a full moon while overlooking the many nights when nothing extraordinary happens. The Moon”s visibility makes it an easy target for blame, unlike hidden factors such as stress, caffeine consumption, or late-night technology use.
Although the Moon may not be the source of our sleeplessness, its influence on sleep emphasizes a crucial point: nighttime light exposure matters.
Our bodies are naturally attuned to follow light and dark cycles. Excessive light in the evening, whether from moonlight, streetlights, or electronic devices, can disrupt circadian rhythms, lower melatonin levels, and lead to fragmented sleep. This biological response can also help explain the health risks associated with daylight saving time. When clocks “spring forward,” evenings remain artificially bright, delaying sleep and disrupting circadian rhythms on a larger scale, which can increase the likelihood of accidents and cardiovascular issues, as well as compromise workplace safety.
In today”s world, artificial lighting exerts a far greater influence on sleep than the Moon ever could. This is why many sleep experts advocate for the adoption of permanent standard time, which aligns better with our biological needs.
If you find yourself tossing and turning on a full moon night, you may not be imagining it; the Moon can indeed affect your sleep. However, if you frequently struggle with sleeplessness, it is advisable to examine the light sources around you, as they are more likely to be the cause than the celestial body above.
This article has been adapted from a piece originally published by The Conversation.
