A circadian rhythm is an intrinsic ability that allows organisms ranging from plants and fungi to humans to anticipate the cyclic changes in the temperature and light in a day. For humans especially, this allows for certain regulatory systems and processes to occur at certain intervals, these being hormone release, metabolism, and blood pressure among other functions (Buhr & Takahashi). Disruption of this cycle can lead to many harmful effects on the body, as it throws everything out of control. Studies on mice and rats have shown that eating food or being exposed to light at unconventional hours brings unneeded stress onto the body, and can spiral into disorders in the long run. Translating it to humans, those who shift their circadian clocks too much have a higher risk for metabolic and cardiovascular disease. Flight attendants and graveyard shift workers are examples of people who are more likely to be exposed to such diseases and disorders (Koch, Leinweber, Drengberg, Blaum, Oster).
Therefore, it is important to keep many parts of the human circadian clock in mind. Keeping a consistent sleep schedule is one of the major points to take into mind in maintaining a good circadian rhythm, as many people note. Another thing to note is the body's food intake. Eating dinner 4 hours before sleeping without any food in between allows for the body to fully switch from the alert state of the day to the restful portion of the night.
References:
Buhr ED, Takahashi JS. Molecular components of the Mammalian circadian clock. Handb Exp Pharmacol. 2013;(217):3-27. doi: 10.1007/978-3-642-25950-0_1. PMID: 23604473; PMCID: PMC3762864.
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ReplyDeleteNathan,
ReplyDeleteAs someone who has rotated pushing late hours working in the hospital, early morning and late night study sessions, and also just maintained generalized disorganization regarding sleep hygiene over the past few years, your admonitory post regarding cardiovascular and metabolic risk with these habits does not go unnoticed.
That being said, you've got me thinking about the period by which these circadian rhythm interruptions begin to accumulate risk for these types of diseases. How long must an individual experience circadian rhythm interruptions for incidences of these types of diseases to increase? It seems rather unethical for a research team to ask participants to commit to long-term sleep disruption in order to gather information on cardiovascular and metabolic disease incidence, which perhaps explains why most of the articles which I found were rooted cross-sectional studies.
That being said, I did find another avenue of interest which stems from my original question - the idea of "sleep debt". Yuki et. al summarized the idea of sleep debt as the "sleep deprivation that accumulates after having short sleep over several consecutive days", and highlighted that two consecutive weeks of 6 hour sleep nights resulted in a decrease in cognitive performance mirroring that seen after an entire night of no sleep at all (Yuki, 2017). Other effects of continued sleep debt include mood disturbances. As this type of sleep disruption is smaller scale, it seems more likely to "go under the radar", especially in comparison to the sleep disruption one may think of when speaking with a night-shift worker. Regardless, I would assume that after reading this, continuous, smaller-scale disruptions in circadian rhythm are not incapable of contributing to the same health effects which you highlighted, and could personally entertain the idea that continued sleep debt/circadian rhythm interruption could have a "point of no return" causative affect on them as such.
Motomura, Y., Kitamura, S., Nakazaki, K., Oba, K., Katsunuma, R., Terasawa, Y., Hida, A., Moriguchi, Y., & Mishima, K. (2017, June 30). Recovery from unrecognized sleep loss accumulated in daily life improved mood regulation via prefrontal suppression of amygdala activity. Frontiers in neurology. Retrieved October 2, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491935/