Work breaks — both physical and digital — play an important role in productivity and workplace wellbeing. Yet, the growing availability of digital distractions from online content can turn breaks into prolonged “cyberloafing”. In this paper, we present UpTime, a system that aims to support workers’ transitions from breaks back to work–moments susceptible to digital distractions. Combining a browser extension and chatbot, users interact with UpTime through proactive and reactive chat prompts. By sensing transitions from inactivity, UpTime helps workers avoid distractions by automatically blocking distracting websites temporarily, while still giving them control to take necessary digital breaks. We report findings from a 3-week comparative field study with 15 workers. Our results show that automatic, temporary blocking at transition points can significantly reduce digital distractions and stress without sacrificing workers’ sense of control. Our findings, however, also emphasize that overloading users’ existing communication channels for chatbot interaction should be done thoughtfully.