Longitudinal observations call into question the scientific consensus that humans are unaffected by lunar cycles

All Light, Everywhere? Photoreceptors at Nonconventional Sites

One of the biggest environmental alterations we have made to our species is the change in the exposure to light. During the day, we typically sit behind glass windows illuminated by artificial light that is >400 times dimmer and has a very different spectrum than natural daylight. On the opposite end are the nights that are now lit up by several orders of magnitude. This review aims to provide food for thought as to why this matters for humans and other animals. Evidence from behavioral neuroscience, physiology, chronobiology, and molecular biology is increasingly converging on the conclusions that the biological nonvisual functions of light and photosensory molecules are highly complex. The initial work of von Frisch on extraocular photoreceptors in fish, the identification of rhodopsins as the molecular light receptors in animal eyes and eye-like structures and cryptochromes as light sensors in nonmammalian chronobiology, still allowed for the impression that light reception would be a relatively restricted, localized sense in most animals. However, light-sensitive processes and/or sensory proteins have now been localized to many different cell types and tissues. It might be necessary to consider nonlight-responding cells as the exception, rather than the rule.

Is there an association between the lunar phases and hospital admission for different episode types in bipolar disorder? A retrospective study in northern China

The effects of the moon on mental activities remain contentious. Few studies have investigated associations between lunar phases and different types of bipolar disorder (BD) episodes. In the current study, 7,452 patients with BD from three hospitals were enrolled. Patients were divided into two groups on the basis of episode types, and the effects of lunar phase were examined for each type. The cosinor analysis revealed moon-related rhythmicity in admissions for BD in a period of 14.75 days. There were fewer admissions around the new moon and the full moon. There was no significant difference between different groups in acrophase. There was possibly a temporal lag between the onset of BD and hospitalization. Thus, it is too early to draw firm conclusions about the impact of lunar phases on BD. Sleep might be a middle way from moon effect to admissions of BD. These results have implications for future disease prevention strategies and research.

Common multi-day rhythms in smartphone behavior

The idea that abnormal human activities follow multi-day rhythms is found in ancient beliefs on the moon to modern clinical observations in epilepsy and mood disorders. To explore multi-day rhythms in healthy human behavior our analysis includes over 300 million smartphone touchscreen interactions logging up to 2 years of day-to-day activities (N401 subjects). At the level of each individual, we find a complex expression of multi-day rhythms where the rhythms occur scattered across diverse smartphone behaviors. With non-negative matrix factorization, we extract the scattered rhythms to reveal periods ranging from 7 to 52 days - cutting across age and gender. The rhythms are likely free-running - instead of being ubiquitously driven by the moon - as they did not show broad population-level synchronization even though the sampled population lived in northern Europe. We propose that multi-day rhythms are a common trait, but their consequences are uniquely experienced in day-to-day behavior.

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.

Prostaglandin E2 synchronizes lunar-regulated beach spawning in grass puffers

Many organisms living along the coastlines synchronize their reproduction with the lunar cycle. At the time of spring tide, thousands of grass puffers (Takifugu alboplumbeus) aggregate and vigorously tremble their bodies at the water's edge to spawn. To understand the mechanisms underlying this spectacular semilunar beach spawning, we collected the hypothalamus and pituitary from male grass puffers every week for 2 months. RNA sequencing (RNA-seq) analysis identified 125 semilunar genes, including genes crucial for reproduction (e.g., gonadotropin-releasing hormone 1 [gnrh1], luteinizing hormone β subunit [lhb]) and receptors for pheromone prostaglandin E (PGE). PGE₂ is secreted into the seawater during the spawning, and its administration activates olfactory sensory neurons and triggers trembling behavior of surrounding individuals. These results suggest that PGE₂ synchronizes lunar-regulated beach-spawning behavior in grass puffers. To further explore the mechanism that regulates the lunar-synchronized transcription of semilunar genes, we searched for semilunar transcription factors. Spatial transcriptomics and multiplex fluorescent in situ hybridization showed co-localization of the semilunar transcription factor CCAAT/enhancer-binding protein δ (cebpd) and gnrh1, and cebpd induced the promoter activity of gnrh1. Taken together, our study demonstrates semilunar genes that mediate lunar-synchronized beach-spawning behavior. VIDEO ABSTRACT.

Biological rhythms: Hormones under moon control

Grass puffers are fish that engage in mass spawning controlled by the phase of the moon. A new study shows that prostaglandins released by males and females fine tune these events. In addition, regulation of gnrh1 by a transcription factor expressed in a semilunar rhythm suggests a timing signal for the long-term coordination of gonadal maturation.