Introduction: This field study tested the effectiveness of quiet hours (an hour free of any phone calls, visitors or incoming emails). Objective: Based on interruptions research and on a behavioral decision-making approach to time management, we argue that establishing quiet hours is a precommitment strategy against predominantly harmful interruptions. Furthermore, conscientiousness and the use of other time management techniques should moderate the effects of the quiet hour. Method: We tested this by using a two-week experimental diary study with managers as participants. Results: Multi-level analyses showed that a quiet hour improved the performance on a task worked on during the quiet hour in comparison to a similar task on a day without a quiet hour. Furthermore, overall performance was higher on days with a quiet hour than on days without one. Conscientiousness acted as a moderator, unlike the use of other time management techniques. Conclusion: These results imply that more people should consider implementing a quiet hour, especially if they are non-conscientious.