Circadian Rhythms exert a powerful, invisible force that coordinates the day-to-day activities of our body, and addition to our sleep cycle, these subconscious rhythms regulate everything from blood pressure and body temperature to stress and alertness. The body's internal clock functions by a timed molecular feedback loop in the Suprachismatic Nucleus, where Clock genes express Clock proteins, inhibiting the genes until the proteins are degraded, allowing more Clock proteins to be synthesized and so on. The whole process takes a little under 24 hours, and persists even in the absence of light cues. However, light plays a crucial role in synchronizing the clock, effectively aligning biological rhythms to the day/night cycle of the environment. The problem arises when the lights don't go out when the body expects them to -- whether it's jet lag, going out with friends, or staying up late studying for that final you need a really good grade on, a whole mess of things go wrong when we mess with our circadian rhythm.
Dr. Cavanaugh's research on circadian disruption in fruit flies (Drosophila) revealed that exposing flies to long periods of circadian misalignment lead to a nearly 15% reduction in lifespan in both males and females. The advantage using Drosophila as an experimental model is the comprehensive genetic toolkit that scientists have developed for it over the last half a century. By using whole-body RNA-sequencing techniques, Dr. Cavanaugh was able to analyze the differences in gene expression between normal and circadian-misaligned flies, which revealed upregulation in genes involved in oxidative stress, immune response, and aging. It is no surprise that a genetically coordinated system like the suprachiasmatic circadian clock has harmful genetic effects when it becomes misaligned. The question then becomes how these effects play out in humans, and more importantly, how much sleep I can miss during finals before I endure lasting, permanent consequences to my health and my exam scores.
A 2017 Harvard study by Andrew Phillips et al. sought the answer to the latter, investigating how "irregular sleep/wake patterns are associated with poorer academic performance." By establishing a scale that measured how consistently 61 Harvard undergrads got their snooze on, the researchers were able to come up with a Sleep Regularity Index (SRI) that measured the likelihood of a student being awake/asleep at the same point of the day 24 hours apart. In other words, someone who went to bed and woke up at the same time every day would be at a 100, with lower scores indicating greater irregularity in sleep schedule. The researchers found a 1:1 correlation between SRI and GPA, with every point lower SRI correlating to a .01 drop in GPA. The gap between the most regular sleepers and the most irregular represented a .40 point gap, not overwhelming, but still significant. More interestingly, they found no significant correlation between the amount of sleep and GPA, rather it was the regularity of sleep onset that was the biggest predictor of GPA. However, this doesn't mean you should sleep 3 hours a night at the same time every night, but those who sleep naturally less are not at so great a disadvantage.
From this data, I surmise that I should adjust my approach to sleeping during this finals week. It is clear that sleep plays a big role in academic performance, but personally I have trouble falling asleep, so 8 hours a night is rarely feasible, and 6 is usually the norm. If, as the Harvard study claims, consistency is more important than quantity, then it is not the length of my sleep that matters as much as when I fall asleep. I suspect that the innate pattern circadian rhythm itself is not as important as preventing its disruption. As with studying and exercise, consistency is key.
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