Long and Short Durations of Binaural Beats Differently Affect Relaxation: A Study of HRV and BRUMS

Objective: We aimed to identify parasympathetic and emotional alterations, as indicated by the heart rate variability (HRV) and Brunel mood scale (BRUMS), after long-term exposure to theta binaural beats (BB) for 10 minutes daily. Methods: Recruited healthy subjects (n = 60) were equally split into the experimental and control groups. HRVs were measured over three visits spaced out by two weeks. At each visit, HRV was measured for two minutes before, ten minutes during, and two minutes after listening. Results: The root-mean-square of differences between successive RR intervals (RMSSD) and the percentage of adjacent RR intervals with a difference greater than 50 ms (pNN50) were significantly increased during 6-Hz BB listening at 4–10 minutes at all three visits, but high frequency (HF) HRV was increased at the second and third visits. After 6-Hz BB listening, there were significant increases in RMSSD and pNN50 at the second and third visits, and in HF HRV at the third visit. BRUMS demonstrated a significant decrease in both positive and negative moods after listening to 6-Hz BB on the first visit. However, after two and four weeks, BRUMS demonstrated a significant decrease in only negative mood. Conclusion: A minimum of four minutes of 6-Hz BB could be beneficial to improve relaxation during listening. However, considering the aftereffects, two weeks of daily listening might be required to achieve deep relaxation without vigor reduction. Significance: Optimal duration and practice of BB listening are the keys to achieving better relaxation and parasympathetic tone in healthy listeners.