Analgesic and Sedative Effects of Blue LED Light in Combination with Infrared LED Irradiation

Abstract

INTRODUCTION: Our previous studies have shown that polarized red+infrared LED light causes analgesic effect. The aim of this study was to test whether the blue LED light has such effect. We compared the analgesic efficacy of continuous blue light without infrared component and in combination with infrared irradiation. We also determined the dependence of responses on frequency of pulsation of blue+infrared (blue+IR) LED irradiation. METHODS: We used the model of experimentally induced chemical inflammation (formalin test). The source of the light emission was MEDOLIGHT-BluDoc device. In animals (white mice males), we recorded the duration of pain (licking the affected limb) and non-painful (sleeping, washing, running, food) behavioral reactions with placebo (control) and after the 10-minute light application on the locus of pain. The influence of continuous (blue or blue+IR) and pulsed (frequency of pulsations 10 Hz, 600 Hz, 3000 Hz and 8000 Hz) (blue+IR) light was determined. RESULTS: After the application of blue LED light without infrared component or with infrared radiation duration of pain response decreased to 317.3 s and 282.3 s against 566.2 s in the control group. Analgesia was 43.6% and 50.1%. Pulsed blue+IR LED light (all the tested ranges) also significantly reduced pain. Analgesia was maximal at a frequency of 8000 Hz (57.6%) and minimal at a frequency of 10 Hz (38.3%). Duration of sleep in experimental groups was 2.3-3.8 times longer than in the control group, the effect was most noticeable at frequency of 10 Hz. Conclusion: It was found that the blue and blue+IR LED light MEDOLIGHT-BluDoc device (both continuous and pulsing mode) when applied to a painful inflammation area possess a significant analgesic and sedative effect.