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Sleep Irregularities May Increase Cardiovascular Health Risks, According to VUMC Study

Supriyo Rana | April 14, 2023

Sleep, or rather lack thereof, is a pronounced issue in most colleges around the country. The problem is particularly widespread at more academically rigorous universities, such as Vanderbilt University. Between academics, student organizations, and social activities, students often sacrifice sleep to balance their commitments.

 General lack of sleep is not the only critical sleep issue affecting students, however. Varying amounts of sleep each night or experiencing disrupted sleep, known as sleep irregularity, can be just as harmful as getting an inadequate amount of sleep. A recent Vanderbilt University Medical School (VUMC) study, led by Dr. Kelsie Full, MPH, suggests that sleep irregularities may increase the risk for atherosclerosis. Atherosclerosis is the buildup of fats, cholesterol and other substances (collectively known as plaque) in and on the artery walls. There are currently no treatments to cure atherosclerosis, and lack of early atherosclerosis detection through CT scanning may eventually lead to a heart attack or a stroke. Therefore, it is important for young college students to get enough consistent sleep to minimize their risk for developing atherosclerosis in the future. 

The week-long study’s participants included 2,032 older and racially and ethnically diverse participants from six communities around the United States. The study excluded shift workers (who are known for having irregular sleep patterns) and those with existing heart disease. Sleep regularity was measured by the 7-day standard deviation (SD) of sleep duration and sleep onset timing. The larger the standard deviation, the more irregular a participant’s sleep was. Participants with a standard deviation of greater than 2 hours of sleep over the week exhibited higher burden of coronary artery calcium and more plaque in their carotid arteries compared to those with a standard deviation of less than or equal to 1 hour of sleep over the week.

The results of this study imply that by adjusting sleep regularity, atherosclerosis risk can be reduced. Thus, encouraging regular sleep schedules may be an important part of clinical lifestyle recommendations for the prevention of cardiovascular disease. The reason for this is likely because most major cardiovascular functions, such as heart rate and blood pressure, are regulated by circadian rhythms. Thus, the disruptions of these circadian rhythms can interrupt these important cardiovascular functions, contributing to the body’s “fight-or-flight” response, increasing arterial pressures and leading to atherosclerosis progression.

There is currently no targeted research done on the long-term effects of sleep irregularities. However, the stark contrast in the study’s measures of subclinical atherosclerosis between the “consistent sleep” and “inconsistent sleep” groups in just one week indicates that long-term effects of sleep irregularity may exist. For example, one study funded by the National Institute of Health (NIH) showed that irregular sleep schedules can put a person at a higher risk for obesity, high cholesterol, hypertension, high blood sugar, and other metabolic disorders. Additionally, high sleep variabilities can lead to mental health concerns such as sleep deprivation, depression, impaired memory, and increases the risk of other health conditions. 

It can be challenging to keep a consistent sleep schedule as a college student. Luckily, improving your sleep schedule is not the only way you can improve your sleeping habits. Restricting time spent in bed, avoiding daytime napping, and restricting caffeine late in the afternoon are just a few ways that students can get more regular sleep and improve their health. Future studies should be conducted, however, to better understand the connection between sleep irregularity and physical and mental health impairments, which may lead to the prevention of such conditions.

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