This diary study examined within-person effects of positive work and off-work experiences on daily engagement levels. Assessing the gain cycle assumption of conservation of resources theory, we investigated the relationship of night-time recovery and subsequent resources including elevated sleep quality and morning positive affect; the relationship of morning positive affect with positive collegial interactions and subsequent engagement; and the relationship of engagement with night-time recovery. Sixty-nine employees from various occupations completed surveys three times per day, over five consecutive working days. Multilevel analyses revealed that sleep quality positively predicted morning positive affect, which in turn predicted engagement directly and also indirectly through having positive interactions with colleagues. Engagement positively predicted night-time recovery, while night-time recovery was not related to sleep quality or morning positive affect the next day. The results suggest that on days when individuals have a good night’s sleep, they feel more positive, bring this positivity to their workplace, reach out to their workplace colleagues, and are in turn more likely to be engaged in their work. Additionally, on days when individuals experience higher levels of positive collegial interactions at work and in turn higher engagement, they are likely to experience better recovery.