Nate Goodwin (left), Dr. Michael Brian (middle) and Gabe Dennett (right). Photo credit: Jeremy Gasowski
I am a rising senior in the Exercise Science program, and my colleague, Gabe Dennett, and I are conducting research with a Summer Undergraduate Research Fellowship (SURF) under the mentorship of Dr. Michael Brian in the Robert Kertzer Exercise Physiology Laboratory at New Hampshire Hall. We are running a group project with two distinct aims. My focus is to assess the effects of an acute model of circadian misalignment on central blood pressure, heart rate variability, and inflammation. Gabe is focusing on the impact of such a disrupted sleep schedule on substrate utilization and exercise capacity. You may not have heard of some of those terms before, so I’ll explain them in a little further detail, as well as how we work together in the lab!
One of the main reasons why we wanted to investigate irregular sleep patterns was because it is so prevalent among the college population. During the week, students might follow a rigorous sleep schedule due to class commitments, but on weekends, it is not maintained due to no classes and/or social events. This irregularity of circadian patterns is termed “social jet lag,” which has been demonstrated to cause risk for cardiometabolic diseases. Therefore, it was our goal to design a study protocol that mirrors this habitual experience among college students. Please read Gabe’s blog post, in which he explains more about the significance of social jet lag. Here, I will describe our overall data collection process.
As of mid-August, we have had 10 participants complete the study, so we are very near to reaching our goal of at least 12. Our study population is recreationally active young adults, aged 18-25. The study consists of two, 4-day periods which participants complete in a randomized order. The standardized sleep schedule consists of the same sleep/wake times across the 4 days, and the misaligned sleep schedule consists of sleep/wake times shifting ±1 hour around the standardized period’s times, every other night. For example, if standard sleep is 11 P.M. sleep onset and 7 A.M. wake, misaligned sleep would be 10 P.M. sleep onset, 6 A.M. wake, and 12 A.M sleep onset, 8 A.M., every other night. The most important aspect is maintaining 8 hours of sleep throughout the duration of both periods! Rather than studying sleep deprivation, we are emphasizing the regularity of sleep duration about these irregular timing of sleep habits.
Participants make three visits to the lab, one for baseline measurements before their first 4-day sleep intervention begins, and one after each 4-day sleep intervention. The first visit consists of some paperwork, demographic measurements such as height, weight, and body composition, and fasting blood glucose and lipids, which Gabe and I work together to collect. These baseline measurements help give a better understanding of the study population, and how our main measurements may be influenced by these variables. Then, I measure resting heart rate variability and blood pressure, and a blood draw is performed by Dr. Brian for later analysis of inflammation.
The two post-sleep intervention visits are the same as the first, excluding the demographic measurements and fasting blood biomarkers. For the post-intervention visits, I begin data collection for my focus of the study. The first thing I do is place a heart rate monitor around the participants chest, and a brachial blood pressure cuff around their left arm. Then, participants rest quietly on our examination bed for 5 minutes while the lights are dimly lit. This is to ensure that they are relaxed, and the measurements are controlled. After the 5 minutes is up, I begin the heart rate variability measurement. Heart rate variability is the duration in between each of the heart’s beats. It can tell you a lot about if the body is in a state of stress. Shorter intervals reflect increased sympathetic nervous system activity (the body’s fight or flight mechanism), and longer intervals reflect increased parasympathetic activity (the body’s rest and digest mechanism). One thing that is pretty neat about this data collection is that we are measuring it with a phone app! The heart rate monitor uses Bluetooth to connect to the app and I get all the data right on my phone.
The next assessment I complete is central blood pressure. This is not your typical blood pressure measurement you might get at the doctor. The system we use first measures your brachial blood pressure (the typical measurement), and based on that measurement, it uses a function to predict the blood pressure in your aorta, the major artery that moves blood out of your heart and to all areas of your body. I perform these first two measurements (heart rate variability and central blood pressure) while participants lay quietly on the examination bed. Lastly, Dr. Brian, performs a blood draw. About 10 minutes after the blood draw is done, I put the test tube in the centrifuge and prepare to pipette the sample. Learning how to pipette and handle blood has been one of the more valuable technical skills that I have learned this summer! Handling the test tubes with care to ensure safety and a clean sample is super important for quality data. After I complete all my steps with the participant, Gabe takes over and runs the metabolic flexibility protocol for his portion of data collection, with which I assist. Oncewe have blood samples for all 12 participants, the final step we will complete is immunoassaying for analysis of C-reactive protein, an inflammatory cytokine found during times of stress.
My research experience this summer has been extremely valuable. I have learned so many skills that have not only enhanced my technical abilities, but also provided a deeper appreciation for physiology and human subject research. This experience has confidently prepared me for future endeavors in academics and any career path in healthcare and/or research. I am so grateful for the support from my mentor and the Hamel Center, and the opportunity to create meaningful research that addresses real-life concerns. My one message to anyone that is passionate about their field is that if you are presented with an opportunity to do research, take it!
