Circadian Rhythm Disruption

Just about every living organism runs on a near 24-hour process called a circadian rhythm. These cycles determine sleep/wake cycles, metabolism, hormone release, and almost every other physiological process, as well as many behavioral processes. Because each of these processes are dependent on the same cycle, they are intertwined, and so maintenance of this cycle is detrimental to health and wellbeing.

 Dr. Daniel Cavanaugh discussed his research on the topic with our neuroscience class on January 28th. His focus is on feeding behavior in Drosophila, commonly known as fruit flies. His paper “A circadian output center controlling feeding:fasting rhythms in Drosophila” discusses his research. In his lab, he was able to map out neural pathways in flies related to circadian rhythms, and track how they responded to circadian rhythms. He was able to find pathways with circadian output areas which were active during specific processes. Metabolism interacts with sleep pathways, feeding:fasting interacts with sleep pathways, and rest:activity interacts with light pathways. All of this research shows just how intertwined physiological processes are due to circadian rhythms.

 Because they are so intertwined, disrupting one must also disrupt others. This disruption was explored in another article, “Effects of Chronic Social Defeat Stress on Sleep and Circadian Rhythms are Mitigated by Kappa-Opioid Receptor” where Dr. Audrey Wells discusses the effects of stress on circadian rhythms, especially sleep. This study was done on mice, stimulating them with CSDS, which was meant to mimic stressful situations for humans. She found that sleep and circadian rhythms were majorly disrupted when mice were affected with CSDS. The disruption to sleep and circadian rhythms was measured by tracking irregularities in body temperature and motor activity. These findings show that one disruptor, in this case stress, can affect multiple systems, such as sleep, body temperature, and regular motor activity.

 Although Dr. Cavanaugh’s feeding:fasting research and Dr. Well’s stress research were done on nonhuman organisms, their findings are extremely relevant. Because all animals have circadian rhythms, research showing the negative effects of disruption on certain animals should be thought of in terms of all organisms, even if the exact brain structures and neural pathways effected are not common to all. However, the results of this research should be taken as reasons to study human circadian rhythms more closely. It is already proven that these rhythms are commonly disrupted and vitally important. Looking at this research, humans should feel more inclined to pay attention to their sleep schedule, eating schedule, and the amount of artificial light they are exposed to when it is not light outside. Researchers should feel more inclined to study the real pathways in the central nervous system that are associated with circadian rhythms rather than coming to conclusions based only on correlation. Circadian rhythms effect all living organisms, and in order to be healthy, humans should pay more attention to how they support these systems and avoid disruption.

 Dreyer AP, Martin MM, Fulgham CV, Jabr DA, Bai L, Beshel J, et al. (2019) A circadian output center controlling feeding:fasting rhythms in Drosophila. PLoS Genet 15(11): e1008478. https://doi.org/10.1371/journal.pgen.1008478

 Wells AM, Ridener E, Bourbonais CA, Kim W, Pantazopolous H, Carroll FI, et al. (2017) Effects of Chronic Social Defeat Stress on sleep and circadian rhythms are mitigated by kappa-opioid receptor. Journal of Neuroscience 37(32): 7656-7668. https://doi.org/10.1523/JNEUROSCI.0885-17.2017