Effect of exposure to short-wavelength light on susceptibility to motion sickness
This randomized cross-over study tested the hypothesis that exposure to short-wavelength light induces symptoms of motion sickness (MS). The study participants were 28 healthy adults (14 women; mean age±SD, 25.96±3.11 years). Two stimuli oscillating within a range of 0.4–0.6 Hz were used to induce MS: a blue wave stimulus with short-wavelength light (460 nm) and a green wave stimulus with middle-wavelength light (555 nm). All participants were exposed to both stimuli throughout two separate periods. After a baseline period, participants were exposed to each stimulus three times for 4 min. The Simulator Sickness Questionnaire, a self-report checklist composed of three subscales (Oculomotor, Disorientation, and Nausea), heart rate variability, and electrogastrography were used to measure the degree of symptoms related to MS. A linear mixed-effects model was used for statistical analysis. The results showed significant main effects for Period (P<0.01), Color (P<0.01), and Time Point (P<0.01) scores on the Simulator Sickness Questionnaire Nausea subscale. A post-hoc test indicated that scores on the Nausea subscale were significantly higher after the third exposure to blue light than after the first and second exposures. The linear mixed-effects model showed significant main effects for Color (P<0.01) with respect to the normogastria/tachygastria ratio. These findings suggest that short-wavelength light induces symptoms of MS, especially gastrointestinal symptoms.