Effects of color temperature and time gradients on visual fatigue recovery in closed cabin

The working environment of a closed cabin is particularly prone to inducing visual fatigue among visual display terminal (VDT) operators. Once visual fatigue symptoms set in, the limited space of the closed cabin and its monotonous visual environment make it challenging to alleviate visual fatigue by disregarding the fatigue. Fifteen healthy male participants aged 20–25 years were recruited for the study, and the results were statistically significant. The fatigue recovery degrees under three lighting color temperatures (3000 ​K, 4500 ​K, and 6000 ​K) and three recovery durations (5 ​min, 10 ​min, and 15 ​min) in a closed cabin were studied. The visual fatigue scale and the Karolinska Sleepiness Scale were employed to collect subjective fatigue data from the participants, while objective visual fatigue data were obtained using an eye tracker. After 5 ​min of rest, the rate of change in pupil diameter at low temperatures was significantly greater than that at high temperatures (P ​= ​0.033). The results indicated that recovery under the 3000 ​K light environment was beneficial for alleviating and eliminating visual fatigue, while a 6000 ​K light environment helped improve the alertness of VDT operators. Recovery time significantly impacted the recovery degree of visual fatigue, with the recovery degree increasing as recovery time increased. Color temperature and recovery time interacted significantly (P ​= ​0.011), and the light environment parameters showed a significant impact only at short recovery times. This paper also introduced a visual fatigue recovery index to measure the degree of visual fatigue recovery, and the index was used to verify the experimental results. The research holds significant reference value for selecting ambient lighting color temperatures in resting rooms.