We present computer simulations of sensitivity changes obtained during single aliquot, regeneration procedures. The simulations indicate that the sensitivity changes are the combined result of shallow trap and deep trap effects. Four separate processes have been identified. Although procedures can be suggested to eliminate the shallow trap effects, it appears that the deep trap effects cannot be removed. The character of the sensitivity changes which result from these effects is seen to be dependent upon several external parameters, including the extent of bleaching of the OSL signal, the laboratory dose used and the natural dose. However, the sensitivity changes appear only weakly dependent upon added dose, suggesting that the SARA single aliquot technique may be a suitable method to overcome the sensitivity changes. (C) 1997 Elsevier Science Ltd.