Use of portable devices to measure brain and heart activity during relaxation and comparative conditions: Electroencephalogram, heart rate variability, and correlations with self-report psychological measures

Abstract

Recent technological advancements have enabled the development of portable devices that facilitate psychophysiological measurement in ecologically valid settings. The aim of the present study was to establish normative heart rate (HR), heart rate variability (HRV), and electroencephalogram (EEG) power during relaxation and comparative conditions. Fifty healthy adult participants completed baseline psychological questionnaires and subjective ratings of relaxation while portable devices measured continuous EEG, HR, and HRV data during eyes-open (EO) and eyes-closed (EC) resting, relaxation induction, and patting a toy dog (TD). Subjective relaxation levels were higher after the relaxation and TD compared to EO and EC resting conditions. Psychophysiological indications of relaxation included higher HRV during relaxation, and higher delta, theta, and alpha power during the TD condition. EEG recorded using a portable wireless single-channel device showed frontal EC versus EO differences comparable with those reported using traditional laboratory-based EEG equipment. Additionally, alpha power was positively correlated with resilience and negatively correlated with depression, anxiety, and stress. Delta power correlated positively with subjective relaxation levels during relaxation. Overall, the results suggest that portable devices can provide valid measurements of psychophysiological activity during relaxation outside of laboratory settings. Changes in HRV and EEG waveforms reveal more information about physiological relaxation and show promise for real-world monitoring in fields of study that investigate human arousal, stress, and health.