A model is introduced for explaining the sensitivity change of the infrared stimulated luminescenceonSL) signal used for dating. The model involves the competitions of the two types of traps to captive the electrons creaked in the irradiation process

the sensitivity of the IRSL signal representS the resPOnse of the T

signal charges in the“easy to bleach”trap to the irradiation dose and depends on the concentration of election in the u hard tO bleach“ traps. It predicts that the sensitivity of the IRSL signal can be increased

decreased or unchanged aller laboratory bleaching. The sensitivity change is dependent. on the degree of sunlight bleaching prior to deposition

the age of the sample and the conditions of laboratory bleach. The predictions by the model agree well with resultS reported in the literature. Further more

the model has been tested with a specially designed experiment. The applications to optical dating with regeneration method are discussed.