When using a single-aliquot regenerative dose (SAR) protocol for luminescence dating of sedimentary quartz grains, the fundamental assumption is that the sensitivity of the optically stimulated luminescence (OSL) produced by the regenerative doses can be monitored by their following test dose OSL response. Using well-bleached coarse quartz grains, OSL production in a SAR protocol was studied in detail when dose response curves were constructed using both single and multiple aliquot regenerative dose procedures. During application of the SAR protocol, two preheats are applied, each ahead of an OSL measurement that is produced by the regenerative dose and test dose, respectively. It is shown that sensitivity changes caused by heating were well corrected for using the OSL response to the test dose. However, these preheats are shown to result in thermally stimulated OSL signals that contribute both to the OSL response from the regenerative doses used to construct the dose response curve and to the OSL response from the test dose used to monitor OSL sensitivity changes as the quartz grains are repeatedly measured. A simple test is proposed to identify the contribution of the latter signal.