Occurrence and co-occurrence of nonsuicidal self-injury and disordered eating in a daily diary study: Which behavior, when?

Although research has explored between-person traits that may account for the co-occurrence of non-suicidal self-injury (NSSI) and disordered eating (DE), little is known about within-person processes that predict when each behavior occurs. This study describes the socioemotional contexts of NSSI and DE behaviors during a two-week daily diary period. Young adults (aged 18-35) who reported ≥1 episode of NSSI and ≥1 episode of DE (binge eating, purging, or fasting) during the diary period were included (N=25). NSSI and DE co-occurred approximately one third of the time. Participants were more likely to act on NSSI thoughts following arguments and feelings of rejection. They were more likely to act on binge eating/purging thoughts after eating or watching television, and when they felt self-hatred. They were more likely to act on fasting thoughts after discussing upsetting memories, and when they were in a public setting. NSSI days were marked by more intense negative mood in the evenings relative to fasting days, and greater fatigue in the morning relative to binge eating/purging days. This study underscores the utility of using experience-sampling methods to develop and test within-person models to advance our understanding of co-occurring behaviors.