On April 16, 2019, Dr. Cavanaugh was a guest speaker for Dr. Robert Morrison's NEUR 300 001 course at Loyola University Chicago. His talk was titled "Using Flies to Understand the Circadian Disruption." His research agrees with some of the points made by Professor Anne Skeldon and Professor Der-Jan Dajk at University of Surrey. Skeldon and Dajk discuss the ineffectiveness of implementing a permanent daylight savings time to allow students to begin school later.
Before discussing daylight saving and changing our clocks, it is important to understand the biological clock. Circadian disruption occurs when the biological clock of a species is altered. How this biological clock, known as the circadian rhythm, works has baffled scientists for decades. The circadian rhythm suggests that there are certain rhythms of the body that are regulated like clockwork throughout the day. These rhythms include body temperature, hormone release (specifically cortisol and melatonin), reaction times, alertness, metabolism, muscle strength, and sleep. Scientists believe this is the work of two proteins in the brain, TIM and PER. The production and degradation of these proteins roughly takes (unsurprisingly) 24 hours and likely is an evolutionary trait.
Dr. Cavanaugh's work with fruit flies revealed two interesting observations: 1. a reduction in life span in fruit flies when their circadian rhythm was disrupted and 2. circadian rhythms don't seem to be significantly affected by the environment such as light. Mutations of the TIM and PER proteins (as induced in Dr. Cavanaugh's experiment in fruit flies) and intentional disruption seem to be the largest causes of circadian disruption. Examples of intentional disruption for humans would be social jet lag, shift working, and traveling. Social jet lag occurs when (usually the younger population) has a regular sleep schedule during the week and ignores that schedule during weekends by going out with friends, studying late, drinking, etc. In other words, the Monday blues is a real biological process of circadian disruption. Dr. Cavanaugh's work revealed that a 4 hour difference in circadian rhythms can cause a disruption. In humans, the consequences of chronic disruption is an increase risk for certain diseases such as diabetes, heart disease, cancer, and shortened life spans.
Now, the article of Skeldon and Dajk claims two reasons that permanent daylight savings would not benefit students if schools had delayed starting times. One, later starting times will result in students staying awake later at night. As mentioned above, this is known as social jet lag. Social jet lag greatly impairs cognitive function and alertness that is needed throughout the school day. Research has shown that students that suffer from social jet lag suffer from GPA lowering. Another permanent daylight saving issue is that our biological processes will not adapt to the changes. As we saw from Dr. Cavanaugh's research, starting school or other processes later in the day will not change the bodies natural tendencies to release various hormones at specific times. As Skeldon and Dajk write in their article, waking up later for school will have the same amount of difficulty for students as current timing. Biologically, this is because of the hormone release of cortisol.
As mentioned in Skeldon and Dajk's article, the idea behind circadian rhythms is very complicated and not well understood. But as we can see from Dr. Cavanaugh's data, until we understand the mechanism more, it is important not to mess with. With what we know about circadian disruption, changing school starting times would have very limiting benefits and more consequences. If any students are reading this, the most important piece of information to take away from this research is that it is crucial to our academic success to listen to our bodies signals and sleep schedules.
References
Anne C. Skeldon, Derk-Jan Dijk. School start times and daylight saving time confuse California lawmakers. Current Biology, 2019; 29 (8): R278 DOI: 10.1016/j.cub.2019.03.014
Cavanaugh, D. (2019). NEUR 300: Using Flies to Understand the Circadian Disruption. [lecture notes]
University of Surrey. (2019, April 22). Debate on daylight saving time and school start time. ScienceDaily. Retrieved April 27, 2019 from www.sciencedaily.com/releases/2019/04/190422112809.htm
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