Circadian Rhythm is a 24 hour physiological clock cycle in humans, animals, plants, insects, bacteria and fungi. It is commonly known for regulating sleep but this endogenous process also regulates other physiological processes. Circadian Rhythm also plays a very interesting and significant role in multiorgan function, metabolism, hormonal production and changes, and immunity. The changes occur endogenously through sensory response from lightness and darkness or in other words, changes in day and night. The most common example is, it is very difficult to fall asleep in a bright room while sleep eventually comes in dim light or complete darkness. These are very “natural” response to simply light and darkness but are actually very complex and if faced with irregularity can cause a hormonal imbalance such as obesity or other health problems. Research shows that circadian rhythm is not only important for sleep pattern but also has a huge effect on our appetite as well as eating habits which can lead to weight gain. And weight gain can lead to other health problems.
Dr. Austin Dreyer’s research, A Peptidergic Circuit Links the Circadian Clock to Locomotor, shows the effects of circuit and neuronal links of circadian clock. The research model was Drosophila Melanogaster or simply known as fruit flies. Drosophila makes a good model to study because care and culture requires little equipment and less expense even in large genetic research cultures. Dreyer and colleagues examined their the Drosophila’s circadian rhythm in correlation with feeding behavior and through this examination we can translate these results in human circadian rhythm and feeding behavior. Par Intercerebralis (PI) has shown a possible circadian output which is connected to bodies internal clock information regulated by neuronal signaling. The research was able to prove that a mutation in the DH44-1 receptor and inhibition of this peptide results in disruption of free running period, causing arrhythmia in the locomotion behavior of the drosophila. This mutation effects the glycogen storage and feeding times of drosophila and can cause overeating resulting in obesity.
The article, Disruption of Circadian Clock Linked to Obesity, Diabetes and Heart Attacksis related to previous study, as they talk about obesity by looking at insulin activity that is also controlled by the circadian clock. Insulin is an important hormone that travels through the blood stream and helps break down glucose molecules for energy as well as other metabolic processes. The study specifically looks into the time and “when” you eat and not “what” you eat. It is known that insulin works well during active phase. The study used an approach by keeping the mice in a lit environment, which disrupted their circadian cycle by locking the inactive/fasting phase. It was found that the mice were gaining higher proportion of body fat and gained a lot more weight while they were eating less food. The disruption in circadian clock resulted in obesity due to insulin resistance and that increased the risk of diabetes and cardiovascular disease. The researcher was able to explain similar affect in increased obesity in and diabetes in night-shift workers which also disrupted their insulin cycles and resistance of glucose to insulin.
It is very interesting to see the importance of circadian rhythm which not only controls our sleep patterns but also control many other biological and metabolic cycles. This really makes you wonder people with insomnia and having very irregular sleep patterns and how disrupted circadian rhythm could affect an insomniac. And would irregular sleep patterns result in increased risk of diabetes and cardiovascular disease? Especially being a full time student is another great exam, many times students stay awake hours on end during midterms and finals. These researchers give an insight on how simply not having a regular sleeping pattern can have deleterious effects on a person’s health. Dr. Dreyer’s research also reminds of a law passed in New York in 2003 and later all fifty states ratified similar laws/regulations. The Libby Zion Law, was passed by the Department of Health Code, Section 405 which limits the amount of hours resident physicians’ can work in one week to roughly 80 hours cap from previous 100 hours. The law came in affect after overworked resident physician and intern physician misdiagnosed resulting in death of a college freshman Libby Zion. All of these are great examples of how it is imperative to have an undisrupted circadian rhythm in order to have regular sleep patterns.
Citations
Disruption of circadian clock linked to obesity, diabetes and heart attacks
A Peptidergic Circuit Links the Circadian Clock to Locomotor
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