Innovative Light Therapy: 5. Anti-stress Effects of Polarized Polychromatic and Monochromatic Light from Halogen and LED Sources

: In experiments on laboratory animals ( n = 100) and in examinations of people ( n = 42), the anti-stress effect of low-intensity polychromatic or monochromatic halogen light of the Bioptron device (PILER/PL: 480-3,400 nm, 40 mW/cm 2 ) and LED (light-emitting diode) light of the Medolight-polychrome device (401+467.5+527.5+640.5+940 nm) has been demonstrated objectively. We found out that adult rodents (white mice) showed that 30 min of immobilization stress increased grooming duration by 330%, and after a PL (polarized light) session to acupuncture point (AP) E-36—only by 170%-230% compared to the norm. PL’s anti-stress effect was determined by its wavelength. Researchers found that red light (the long-wavelength part of the visible light spectrum) had a significantly greater anti-stress effect than green light (medium-wavelength). Red PL application reduced stress-induced grooming by 49.2% and other behavioural responses (sleeping, eating, and physical activity) were partially normalized, while green PL reduced grooming by 31% without affecting other behavioural responses. The short-term immobilization stress weakened the somatic pain response (formalin test) by 28.5% and the visceral one (acetate test) by 26.3%. Red PL has a less pronounced analgesic effect on animals under stress than on animals not under stress. In normal conditions, red PL suppressed somatic pain by 54.4%, visceral pain by 64%, and under stress by 31% and 46.1%, respectively. Under the action of low-intensity LED-light on AP, we have obtained experimental evidence of stress reduction in humans. The latent period for falling asleep in the subjects increased from 393.6 ± 47.1 to 749.3 ± 44.4 s under stress. Applying the Medolight-polychrome device to auricular AP weakened post-stress sleep disturbances: the duration of falling asleep was reduced to 512.5 ± 38.6 s. In persons with daytime stress, the frequency of dreams was 49% ± 5.7%, and after a PL session it was 14.79% ± 5.2%. The results of these studies can be used to develop recommendations for reducing stress in humans.