Blue lighting accelerates post-stress relaxation: Results of a preliminary study

Abstract

Several authors have studied the influence of light on both human physiology and emotions. Blue light has been proved to reduce sleepiness by suppression of melatonin secretion and it is also present in many emotion-related studies. Most of these have a common lack of objective methodology since results and conclusions are based on subjective perception of emotions. The aim of this work was the objective assessment of the effect of blue lighting in post-stress relaxation, in comparison with white lighting, by means of bio-signals and standardized procedures. We conducted a study in which twelve healthy volunteers were stressed and then performed a relaxation session within a chromotherapy room with blue (test group) or white (control group) lighting. We conclude that the blue lighting accelerates the relaxation process after stress in comparison with conventional white lighting. The relaxation time decreased by approximately three-fold (1.1 vs. 3.5 minutes). We also observed a convergence time (3.5–5 minutes) after which the advantage of blue lighting disappeared. This supports the relationship between color of light and stress, and the observations reported in previous works. These findings could be useful in clinical and educational environments, as well as in daily-life context and emerging technologies such as neuromarketing. However, our study must be extended to draw reliable conclusions and solid scientific evidence.

Portable System for Real-Time Detection of Stress Level

“…We conducted a study in order to validate our system, following the well-established methodology of previous published stress studies [ 28 , 31 ]. Ten healthy volunteers were involved in the study (five male, five female, age range of 18–23 years, mean age of 20 ± 2 years, all of them novice in stress-related experiments).…”

“…Four EEG electrodes were placed at Fp1, Fp2, F3, and F4 positions of the 10–20 International System using an EEG cap. These positions have been successfully used in stress studies [ 24 , 25 , 27 , 28 , 31 ]. One ECG electrode was placed on the wrist of the non-dominant hand.…”

“…In that session, they performed the Montreal imaging stress task (MIST), a proven methodology that induces psychosocial stress in people [ 41 ]. Despite that there are other well-described stress methods such as the variants of the Trier social stress task [ 42 ], the MIST has been used in a considerable number of stress-related works [ 28 , 31 , 41 , 43 , 44 , 45 ]. It was classified as well-described stress method by a recent review [ 46 ].…”

“…During that session, they stayed laid (resting state with opened eyes) down in a blue-lighted room for 10 min. Blue light was recently proven to accelerate the relaxation process after the MIST in comparison with conventional white light [ 31 ]. In this work, the same room and light were used.…”

“…The muscle activity can be measured by electromyography (EMG). Other studies have demonstrated the relationship between stress and certain brain rhythms measured by electroencephalography (EEG) [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. The skin conductance has also been correlated with stress [ 32 , 33 , 34 ].…”