Software developers, as well as other office workers, experience a high number of interruptions each day. While some of these interruptions can be beneficial, they can also incur a high cost, especially if they happen at inopportune moments. In this talk, I will present research on the use of personal data to reduce interruptions and increase productivity. In a joint project with ABB, we developed the FlowLight, an approach that combines a desk traffic light with an automatic interruptibility measure based on computer interaction data. In a large-scale field study with 449 participants from 12 countries, we found that the FlowLight reduced the interruptions of participants by 46%, increased their awareness on the potential disruptiveness of interruptions and most participants continue to use the FlowLight to this day.