<p>Circadian rhythms are often disrupted by external factors such as shift work, jet lag, or changes in sleep. Misalignment of circadian rhythms is associated with an increased risk of many negative health outcomes, including cardiovascular disease, reproductive issues, and cancer. Circadian disruptions may increase maladaptive decision making, and this may mediate the relation between circadian misalignment and negative health outcomes. Circadian disruptions can be systematically investigated in the animal laboratory, and one type of procedure involves changing the light/dark cycle in the animal vivarium. The current study investigated effects of light/dark cycle changes on delay discounting in eight male Sprague-Dawley rats. The delay-discounting task involved discrete-trial choices between a small, immediate reinforcer and a larger, delayed reinforcer. The delay to larger-reinforcer delivery increased across blocks within each session. During training conditions, a standard 12:12 hr light/dark cycle was in effect (the lights turned off at 6:00 <span>a.m.</span> and turned on at 6:00 <span>p.m.</span>). Effects of changes to the light/dark cycle were observed across five conditions. Overall, percent larger-reinforcer choice, response latency, and body weights were relatively stable across light/dark cycle changes. These results indicate that light/dark cycle changes in isolation may have limited effects on delay discounting. Future research to clarify the relation between circadian disruptions and impulsive choice is discussed.</p>