Effect of Differences in Room Brightness on Postural Control during Light Touch Contact

[Purpose] This study investigated the effects of differences in room brightness on standing postural control with or without light touch contact (LT). [Subjects] The subjects were of 40 healthy young people. [Methods] We tested the center of pressure (COP) oscillation during LT under illumination with fluorescent lamps, miniature bulbs, moonlight, and complete darkness. [Results] When we compared the oscillation between the conditions of LT and Non contact (NC) at various illuminations, all the parameters, except those observed in complete darkness, showed significantly lower values under the LT condition than under the NC condition. Under the LT condition, only the values of Total sway length (TSL), but not of the other two parameters, showed any significant difference; complete darkness resulted in a greater TSL than that found under the other illumination conditions. [Conclusion] These results support the idea that, 1) when a person is not touching objects, it may be necessary to adjust the surrounding illuminance to the level of fluorescent lamps (300 lux), but 2) when a person is performing LT, COP oscillation may not greatly change as long as the illuminance is moonlight or brighter, not complete darkness.