Is there a correlation between your genes and your sleep phenotype? Am I a "morning person" or a "night person"? That's what I am trying to figure out! I did this project because I was curious as to how something like sleep may or may not be determined by something as foundational as your genes, your very DNA!

In this lab, I explored the genotypes of the circadian clock gene Per3, which has been associated with sleep behavior in humans. According to the protocol, in one study, a Per3 allele carrying 4 copies of a VNTR was more likely to be found in people with a preference for morning activities, while 5 copies were more likely to be found in people with a preference for morning activities. A VNTR, variable number tandem repeat, is a short sequence that repeats itself consecutively within a gene. The data on this correlation is not definitive in the literature, but only postulated, which is true for many genetic associations.

I will assess both my genotype using PCR and gel electrophoresis, while also assessing my sleep phenotype by answering a questionnaire. There is no direct causation between sleep genotype and phenotype, but through tests like this, we can gain a deeper understanding of the possible correlation.

Here is some of what I learned! The Per3 gene is known as the circadian clock gene, but what does that actually mean? Whether someone feels sleepy around the same time every day or feels hungry around the same time every day, both of these functions are regulated through the circadian clock. The circadian clocks are internal timekeepers that dictate what times of the day we feel sleepy, energized, hungry, and controls bodily functions needed for homeostasis, such as blood pressure, body temperature, hormone release, and metabolism. All in all, the circadian clock regulates some of the most important aspects of the physiology of our anatomy, and that cycle repeats every day. In humans and other mammals, the hypothamalus houses a structure called the suprachiasmatic nucleus which is considered the master clock. Cells in the master clock vacillate in about 24-hour intervals, which helped scientists discover clock genes such as Period3, which are needed for generating circadian rhythms.

We notice the phenomenon of the circadian clock in plants as well because they have to anticipate the daily transition between light and darkness. Thankfully, through evolution, our circadian clock is set to about 24-hour intervals, and can reset to adjust to external factors. For example, our body naturally feels more tired when it is nighttime, and our circadian clock adjusts to this should the amount of sunlight we get change. That is exactly why when someone goes to a new time zone, most likely on a plane, they experience what we would "jet lag." Within a few days, the person who experiences jet lag adapts to the new time zone, and this ability is called entrainment.

Interestingly, individual cells also have their own circadian clocks, which allow them to conduct their many functions conducive to homeostasis.

Research like this is important because it can help our understanding of genetic associations in general, but of this project, specifically the possible association between Per3 genotypes and circadian clock phenotypes.