Ongoing research of the dark storage test for print images has revealed several factors which influence the results. Although it has been known for many years that exposure to light can ‘bleach’ or whiten media that has yellowed with aging, it has not been studied extensively in the context of its impact on the dark storage test. Investigation into this phenomenon has found that simply exposing yellowed media test samples to office light for a few hours causes measurements to shift by 10%. This research studied how the type, intensity, and length of light exposure affected media at different stages of yellowing. One experimental observation is that some bleached media placed in the dark quickly begins to yellow again and in continued testing is indistinguishable from unbleached media. Moreover, the temporary whitening of media during measurements in the dark storage test is best avoided as it can have considerable repercussions on the data analysis.