The objective of this study is to investigate heart rate variability (HRV) over a period of 24 hours with special focus on patterns during the sleep period. Comparisons were made between sleep and the full 24-hour data. The Polar M430 watch was used to record heart rate (HR) data for about 24 hours, and the subject kept a journal of the activities they performed throughout the day. The data was visualized as heart rate in beats per minute (BPM) as a function of time. To check the accuracy of the Polar watch, a 7-minute recording of HR from the watch was performed simultaneously with a gold standard (IX-TA 220 and IX-ECG12, iWorx, Dover, NH). The data was downloaded into Excel spreadsheet, then analyzed. Analysis included calculations such as: standard deviation, range, mean, and the Fast Fourier Transform (FFT). HR data analysis was performed for the 24hr and sleep period. Since daily activities (which can affect HR) were difficult to control in the study subjects, the sleep period was chosen for more detailed analysis. A trend of lower HR and HRV was seen during sleep. Although the watch had modest accuracy, it was able to show some HR patterns during sleep. FFT analysis of the sleep data suggested existence slow HR cycles(which corresponds one cycle every > 5 minutes).

Thesis Completion




Thesis Chair/Advisor

Mansy, Hansen


Bachelor of Science (B.S.)


College of Engineering and Computer Science

Degree Program

Mechanical Engineering



Access Status

Open Access

Release Date