Investigating the potential link between lunar cycle and multiple sclerosis relapses: a call for further studies

ABSTRACT

Multiple sclerosis (MS) is a debilitating disease that causes inflammation of the central nervous system, resulting in myelin damage and axon degeneration. Although the cause of MS remains unknown, various factors such as sex, latitude, sun exposure, serum vitamin D levels, Epstein Barr Virus infection, diet, microbiota and ethnicity are being studied for their potential roles in the development of the disease. While chronobiological factors such as circadian rhythm and seasonality have been explored for their potential influence on the onset, exacerbation, and/or relapses of MS, the potential influence of the lunar cycle on MS has yet to be studied. Therefore, the authors of this letter call for future studies to investigate the possible effects of the lunar cycle on MS activity and course, given evidence suggesting that the lunar cycle may affect sleep, fatigue, melatonin secretion, and mood state in humans. A deeper understanding of the chronobiology of MS could have practical implications for the development of chronotherapeutic strategies and the prevention or mitigation of MS relapses, potentially improving the quality of life of MS patients.

KEYWORDS:

• Chronotherapy
• circadian rhythm
• environmental exposures
• moon cycle
• neurological disorders
• quality of life

Dear Editor,

Multiple sclerosis (MS) is a devastating disease that causes significant damage to the central nervous system, and it is the leading cause of non-traumatic neurological disability in young adults [1]. Although ongoing research is exploring potential genetic and environmental factors, the exact cause of MS remains unknown. Differences based on sex, the month of birth, latitude, and ethnicity have been revealed [2,3]. In most cases, MS is a relapsing-remitting disease and researchers are exploring external factors, such as stress and vitamin D levels, as well as the month of birth, that may contribute to the risk of MS [2]. The role of low maternal vitamin D levels and ultraviolet light exposure during pregnancy is has also been investigated [2]. Disruptions in innate biological rhythms, such as the circadian rhythm may contribute to (i) An increase in fatigue, and impact the quality of life, mood, and sleep [4,5], as well as (ii) The potential impact on the pathological processes in MS patients.

In MS’ patients, the mechanisms underlying fatigue are largely speculative [6,7]. Several studies argued that lower levels of nighttime melatonin have been observed in MS’ patients, potentially contributing to sleep disturbances and/or fatigue [8,9]. A better understanding of the chronobiological basis of MS could pave the way for targeted chronotherapy and/or result in practical implications in terms of the adoption of ad-hoc strategies to prevent or, at least, mitigate the burden of MS relapses. Glass-Marmor et al. [10] reported that nighttime treatment was more effective, leading to better clinical recovery and patient preference than daytime treatment. The lunar cycle rhythm as one of the biological rhythms might affect human behavior and physiology [11–13]. Several studies reported an association between the period around the full moon and an increased prevalence of sleep disturbances [14–17], anxiety/depression [18,19], fatigue rate [15], and even lower levels of nighttime melatonin in humans [14]. However, other investigations showed no effects of the lunar cycle, as shown by a study in the middle-east football players’ injuries [13]. Biological tides were mentioned as potential causes behind lunar effects on humans [20,21]. This theory has been advanced since the human organism is a microcosm comprised of essentially the same elements as, and in similar proportions to those of the earth’s surface (approximately 80% water and 20% organic and inorganic minerals). This has resulted in speculations suggesting that the gravitation forces of the moon might exert a similar influence upon the water mass of the human microcosm [20]. In this context, Papaseit et al. [22] suggested that the lunar tidal force affected certain biochemical processes in humans. Zimecki [23] suggested that during the full moon, the earth is transiently located between the sun and the moon, and the change in the electromagnetic radiation and/or the gravitational pull of the moon during this phase cannot be overlooked. This likely influences the release of neurohormones or neural activity in humans. Likewise, the solar radiation reflected by the full moon might modify brain activity in humans and/or animals [16,24]. In this context, Rozhkov et al. [19] revealed that the total solar/lunar effect (i.e. the phases of the lunar cycle) made a much greater contribution to the modulation of an emotional state than the gravitation component of the lunar influence perse. They stated that when the moment the full moon approaches, the mood gets worse and trait anxiety increases in a substantial proportion of human beings living in the Arctic region. Rozhkov et al. [19] argued that the gravitation component is the principal contributor to the effect of the moon by a synchronizing effect on the biological rhythms [25]. Previous research [26,27] explained that gravitation could affect the human body through the biogenetic magnetite in the human organism, which role has been pointed out [28], and being thought to influencing both healthy- (effects on stress and/or emotional tension) and sick- individuals with deviations in their cardiovascular system functions (e.g. diastolic blood pressure decreasing when the distance between the moon and earth increases). These geomagnetic activity changes have been associated with various health-related effects, including epileptic seizures, hearts attacks, strokes, sudden infant death syndrome, suicide, and depression [29–38]. Those effects might be explained by the fact that melatonin production is affected by the geomagnetic activity [36,37], which may play a role in the entrainment of human melatonin rhythms [39]. The lunar cycle has therefore a potentially substantial effect affecting sleep and melatonin production in humans [14]. Authors who denied the plausible effects of the lunar cycle on humans argued that the gravity exerted by the moon is a remarkably weak force and could not produce tides in smaller bodies of water such as lakes and some seas, let alone a human body [40]. Considering the above and since, the moon cycle is suggested to impact sleep, fatigue, melatonin secretion, and mood state; we could speculate that attacks or relapses in MS’ patients might be associated with the moon cycle (Figure 1). Thus, further investigations on the effect of the lunar cycle (i.e. moon illumination, tide coefficient, earth-moon distance) [13] on MS first relapse is needed. This could contribute to a better understanding of MS risk factors and progression and inform the development of eventual chronotherapeutic strategies for the prevention or mitigation of MS relapses.

Figure 1. Considerations on how the moon gravitational force and luminosity might affect multiple sclerosis’ relapses in humans.

To investigate the potential link between the lunar cycle and MS symptoms and the first relapse, longitudinal studies could track MS patients over multiple lunar cycles, comparing the occurrence and severity of relapses to moon parameters such as moon luminosity and gravitational force [13,17,27]. Employing such investigations and study designs may help gain a deeper understanding of the possible association between lunar cycle and MS, with implications for chronotherapeutic strategies and the improvement of MS patients’ quality of life. Future investigations into the potential relationship between the lunar cycle and MS-related symptoms and disease activity will need to employ well-designed prospective cohort studies or randomized controlled trials with a large sample size to obtain more conclusive evidence. Additionally, ecological momentary assessment and/or actigraphy could be employed to monitor symptoms and disease activity in real-time, capturing the effect of the lunar cycle on the fluctuation of MS symptoms.

In conclusion, while MS is believed to be the result of the interplay between environmental exposures, genetic- and chronobiological- factors. Circadian rhythms and seasonality may also play a role in symptoms exacerbation. While the lunar cycle’s effect on other neurological disorders has been studied [38], its impact on MS remains unexplored. A deeper understanding of MS chronobiology could have practical implications for enhancing MS patients’ quality of life.

Acknowledgments

The corresponding author, Narimen Yousfi, would like to express her sincere gratitude to the E’Raffeha team for their invaluable support throughout the course of this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.