Eating and Circadian Rhythms

Circadian rhythms are 24-hour internal clocks that our body uses endogenously. Circadian rhythms control our sleep/wake cycles and are influenced by changes in light and dark in the surrounding environment. When our bodies sense light, it signals that it is time to wake up and start the day. When it gets darker, it signals to our bodies that we should go to sleep. Circadian rhythms also influence different hormones and bodily processes, such as our appetite. A common example of disrupted circadian rhythms is when you travel to a different time zone, and your sleep cycle no longer matches the environment (i.e. it is light outside, but your body is ready to sleep). Another example of disrupted circadian rhythms is shift workers, who sleep during the day and work throughout the night.

Austin Dreyer’s talk on “Circadian Regulation of Drosophila Feeding Behavior” demonstrated how Drosophila are similar to humans and have circadian rhythms linked to their metabolism. Altering Drosophila’s circadian rhythm affects feeding, which affects body weight. Also, altering when Drosophila has available food, alters feeding behavior and circadian rhythm. Drosophila are very similar to humans and when food is eaten, it acts as a stimulus that tells our bodies and organs to start to function. When food is taken in late at night, when our organs should usually be resting, our bodies get conflicting signals. The food stimulus signals to our organs to function and metabolize, but the darkness outside signals to our bodies that it is time to sleep and for our bodies to rest. When we eat late at night, we essentially do not give our organs any time to rest, since they are working when they should be resting.

Related to Dreyer’s work, in the article “When We Eat, or Don’t Eat, May Be Critical for Health,” the author states that in humans, coordinating meal times to our circadian rhythms may be beneficial to our health. There is evidence that eating earlier in the day is better for you and is linked to burning more calories and digesting food more efficiently. On the other hand, our organs use the night for rest and repair, so we can function efficiently the next day. If people consume food at night, it throws off the circadian rhythm of their organs, making them work for longer and have less time to recuperate. This disrupts metabolism and is linked to weight gain. In one study, individuals stayed up late for a number of consecutive nights, resulting in weight gain and a decrease in insulin sensitivity. In another study, individuals went to bed later and then woke up later, ended up having higher blood pressure, and impaired blood sugar and insulin control. Most people do these things on a regular basis in our society. There are many individuals who stay up late at night due to deadlines or exams and many others who use the weekend to sleep in. These societal norms throw off circadian rhythms and therefore, could be a significant factor in weight loss/weight gain and overall health. This research is important since obesity is one of the most prevailing issues in the United States and increasingly around the world.  

https://www.nytimes.com/2018/07/24/well/when-we-eat-or-dont-eat-may-be-critical-for-health.html