The effect of examination stress on students’ nocturnal sleep metrics studied with custom ECG holter and accelerometer

Objective. To study the effect of examination stress on nocturnal sleep metrics that can be derived from electrocardiogram (ECG) and accelerometer data. Material and methods. An individual 8-digit, 500 Hz wearable device has been developed to record ECG and 3-channel accelerometer data stream. The device has provided diurnal group monitoring of 29 subjects both in semester training and in the examination session. The data collected were analysed to determine the heart rate variability metrics (based on ECG data), total sleep time and sleep movement activity metrics (based on accelerometer data). Results. The statistical analysis of data obtained has established that the state of examination stress, even in sleep, leads to increase of the central influence on ANS. It results in an increase in energy of the sleep low-amplitude movements, on the background of total sleep time reduction. Conclusion. Two metrics to be derived from the accelerometer data have been introduced to determine the influence of various factors on human sleep. Those are arousal index and low-amplitude movement energy. © 2025 Elsevier B.V., All rights reserved.