Effects of Examination Stress on Students’ Nocturnal Sleep Metrics Studied with Custom ECG Holter and Accelerometer

Objective. To study the impact of exam stress on nocturnal sleep parameters determined from electrocardiogram (ECG) and accelerometer data. Materials and Methods. A personalized wearable device was developed to record ECG and three-channel accelerometer data at a frequency of 500 Hz and a 8-bit resolution. This device was used for day-round monitoring in a group of 29 subjects during studies and exam sessions. The resulting data were analyzed to determine the numerical characteristics of heart rate variability (based on ECG data), total sleep duration, and parameters of motor activity during sleep (based on accelerometer data). Results. Statistical analysis of the data showed that in exam stress, students experienced an elevated central autonomic nervous system influence, even during sleep, leading to an increase in the energy of low-amplitude movements during sleep despite a decrease in total sleep duration. Conclusion. Two parameters calculated from accelerometer data are proposed: the activation index and the energy of low-amplitude movements, which can be used to determine the influence of various factors on human sleep. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.