Insufficient sleep is costly to organizations (e.g., direct health costs, cognitive errors, accident risk, and lower labor productivity). In this current study, we examine another more hidden cost associated with insufficient sleep- unethical behaviors. Using a hybrid field/lab experimental approach, participants were randomly assigned to a week of sleep -restriction or well-rested sleep levels in their at-home (naturalistic) environment prior to decision making. We found that sleep restricted participants cheated significantly more in two honesty tasks, while anti-social choices were, surprisingly, not affected. Because sleep restriction promotes reduced deliberation, these results contribute to our understanding of the cognitive underpinnings of decision making. Importantly, these findings have practical implications to managers who want to reduce dishonesty in the workplace. For example, our results suggest that workplace health promotion programs focused on good sleep hygiene would additionally benefit the company in terms of indirectly promoting ethical conduct in the workplace.and COPY; 2023 Elsevier Inc. All rights reserved.