Light levels at night have significantly increased since industrialization1. During this same period of time, there has also been an increase in the incidence of heart disease. Previous studies have shown that light pollution, which is experimentally called dim light at night (DLAN), disrupts circadian rhythms1-2 and increases the likelihood for developing obesity2-3, but its connection to cardiovascular disease is not known2, 4. My experiments this summer determined if DLAN increased atherosclerosis the mouse aorta. I also analyzed eating behavior to confirm previous studies that DLAN causes a higher proportion of eating to occur during the day than normal2. My research is part of a larger project that focuses on disruption of daily rhythms and heart disease. The project will hopefully give new insight into possible causes of the global increase in heart disease. A greater understanding can lead to prevention and treatment of heart disease.
Dr. Pendergast often reminds everyone in our lab that results will not always support the hypothesis. However, she also says that unexpected or negative results are still relevant and can lead to new experiments. The first couple of rounds of my experiment were mainly just working out kinks in the experimental protocol such as adjusting light levels to set up the DLAN conditions. I also learned new techniques including genotyping using PCR, mouse care, analyzing eating behavior, and aorta dissection and cleaning. Preliminary eating behavior data show that exposure to DLAN may lead to eating at the wrong time of day in mice. The atherosclerosis data obtained so far has shown high levels of atherosclerosis in male mice exposed to DLAN, and normal levels in female mice. Although the sample number is still low, the results do seem to suggest that exposure to DLAN increases atherosclerosis in male mice.
Since I am doing research with mice, mouse care is an everyday task in my research experience. Using mice for experiments is exciting because they provide data simply by being housed in their light-tight boxes with food and water. Getting results and sharing them with the lab is one of my favorite parts of research because it always leads to a discussion of what the results mean and the future directions of the experiment. However, the analysis of this data, such as watching hours of videos of eating behavior, is not the most exciting process. Being part of a research lab is interesting because of the daily discoveries about animal physiology, which lead to thoughtful discussions about how they relate to everyday life. Overall, research has been a valuable experience for me that has strengthened my time management, leadership, and problem-solving skills.
- Fonken, L. K.; Aubrecht, T. G.; Melendez-Fernandez, O. H.; Weil, Z. M.; Nelson, R. J. Dim light at night disrupts molecular circadian rhythms and increases body weight. Journal of biological rhythms 28(4), 262-71, 2013.
- Fonken, L. K.; Workman, J. L.; Walton, J. C.; Weil, Z. M.; Morris, J. S.; Haim, A.; Nelson, R. J. Light at night increases body mass by shifting the time of food intake. Proceedings of the National Academy of Sciences of the United States of America, 107(43), 18664-9, 2010.
- McFadden, E.; Jones, M. E.; Schoemaker, M. J.; Ashworth, A.; Swerdlow, A. J. The relationship between obesity and exposure to light at night: cross-sectional analyses of over 100,000 women in the Breakthrough Generations Study. American journal of epidemiology, 180(3), 245-50, 2014.
- Morris, C. J.; Purvis, T. E.; Hu, K.; Scheer, F. A. Circadian misalignment increases cardiovascular disease risk factors in humans. Proceedings of the National Academy of Sciences of the United States of America, 113(10), E1402-11, 2016.