Our on-device mobile measurement data tracks more than 75 app categories. The data reveals that there are differences in the time at which these categories are accessed on mobile. We picked a few top app genres and analyzed the share of time spent on each by day part. Distinct usage differences can be seen, with mornings devoted to music and video usage picking up at night. Social networking activity is high during evenings. Mobile coupons are accessed more during mornings whereas game and shopping usage peaks at night.