Sleep & Circadian Rhythm

By Jon Esposito Ph.D. candidate, MA, CSCS, USAW, CISSN


Sleep is a very important part of our lives and not getting enough of it can really throw us off. A short blog post cannot even begin to touch on the vast information there is on sleep and how important it is for the human body. Therefore, we will briefly focus on one key factor to pay attention to when it comes to sleep, your circadian rhythm.


Your circadian rhythm is essentially a 24-hour cycle that regulates how your organs and cells behave by aligning the biological functions with the environment. Meaning your body regulates cells in the body for certain organs around certain times of the day. This allows the body to maintain optimum health and disruption of these rhythms can lead to cancer, cardiovascular disease, and much more. Everyone has their own unique circadian rhythm and a simple way to find out what your rhythm is, is to track at what time you naturally begin to feel tired and fall asleep and at what time you naturally wake up (i.e. without an alarm clock or anyone else waking you up). If you look at those times and compare them to the time of sunset and sunrise and they are similar, then you have a good circadian rhythm. If not, then there might be outside factors that are keeping you from a natural circadian rhythm.


There are several things that can keep you from having a natural circadian rhythm. One is blue light, blue light past the hour of sunset can trick the brain into thinking it is still day time and will inhibit the production of melatonin, keeping you up. This is particularly true for most people who scroll through their phones at night, which this study showed does indeed keep you from falling asleep. Furthermore, this study found that children are more sensitive to blue light than adults are and decreasing the amount of blue light at night can significantly improve their sleep. Thus, a few (free) things that can help reduce blue light at night are setting your night time iPhone setting (go to: settings > display & brightness > Night Shift) and set it to the time of sunset and sunrise and toggle the warm setting all the way to more warm and your phone will automatically dim after sunset and brighten during sunrise. Second, is downloading the app f.lux which basically does the same thing your iPhone does, but for your computer.


Another factor that can disrupt your circadian rhythm is your microbiome and the food you eat. This study showed that preclinical research suggests that gut microbes experience diurnal rhythms, and the health effects of eating patterns, including time-restricted feeding and meal frequency, may be related to the GI microbiome. Furthermore, this study showed that a healthier diet promoting good sleep is essential to maintaining gut microbiome balance and disturbances in microbiome rhythms may partially contribute to an increased risk of obesity and metabolic syndrome associated with insufficient sleep and circadian misalignment. Moreover, this study shows the relation between the microbiome, circadian rhythm, and depression as the circadian rhythm is linked to the microbiome which can affect psychological stress.


However, these studies are all preliminary and more research is needed and is being done on the relationship between the microbiome and circadian rhythm but the early data shows you can either regulate or disrupt your microbiome and circadian rhythm through the food you eat and when you eat it.


Thus, some key takeaways are;

  • Find your circadian rhythm and if you are aligned with sunset and sunrise
  • Block blue light at least an hour before bed and preferably right as sunsets, utilize night shift on your iPhone or other, and download the f.lux app
  • Combining the removal of blue light and a healthy diet will improve your sleep quality


There is a vast amount of information on the microbiome and what you can eat and do to help improve your microbiome and it is only recently that the link between circadian rhythm and microbiome has begun to be studied. Therefore, this article only briefly touches on the vast amount of information on sleep and circadian rhythm so if you would like to find out more on how to improve your sleep cycle and circadian rhythm, just inquire within!

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