Influence of daytime blue-enriched bright light on heart rate variability in healthy subjects

ABSTRACT

Heart rate variability (HRV), the indicator of the autonomic nervous system-induced modulation of heart rate, is a focal topic in psychophysiological research. The effect of indoor light on HRV may be related to various psychophysiological functions. The current study (N = 20) examined the response of the autonomic nervous system (ANS) to bright vs. dim blue-enriched light (1200 lx or 200 lx at eye level, 6500 K) exposure for five hours in the afternoon among healthy young adults. The results revealed a significant main effect of light condition on the time-domain indicators, with the significantly higher HRV (SDNN and RMSSD) under 200 lx versus 1200 lx condition, and the same case was revealed for the standard deviations of the Poincaré plot in non-linear effects. Conversely, no significant effects were revealed for the frequency- domain indicators of HRV measured with the subjects’ eyes open. These findings suggested that the autonomic nervous system modulation of HRV was stronger under bright light conditions.

KEYWORDS:

• Light
• illuminance
• autonomic nervous system
• heart rate variability
• time domain
• frequencydomain

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Key Research and Development Program of China [No. 2016YFB0401202], Program for Chang Jiang Scholars and Innovative Research Teams in Universities [No. IRT_17R40], Science and Technology Program of Guangzhou [No. 2019050001], Guangdong Provincial Key Laboratory of Optical Information Materials and Technology [Grant No. 2017B030301007], National Center for International Research on Green Optoelectronics, MOE International Laboratory for Optical Information Technologies and The 111 Project, a program co-financed by Philips Lighting.