★ One possible function of nonsuicidal self-injury (NSSI) is affect regulation. ★ Endogenous opioids may be involved in affect regulation via NSSI. ★ We propose that individuals who engage in NSSI have low resting opioid levels. ★ We also proposed that NSSI releases opioids which regulate affect.
Nonsuicidal self-injury (NSSI), or the purposeful destruction of body tissue occurring without suicidal intent, is a perplexing behavior as it goes against the natural instinct to maximize pleasure and minimize pain. One possible reason that people engage in NSSI is to regulate affect. However, the exact mechanisms that cause NSSI to lead to reduced feelings of negative affect remain unclear. Due to its involvement in the regulation of pain and emotion, the endogenous opioid system has been proposed to mediate the affect regulation effects of NSSI. The authors review evidence from multiple literatures to support this claim. Based on the current research, it is proposed that (1) individuals who engage in NSSI have lower baseline levels of endogenous opioids, (2) NSSI releases endogenous opioids, and (3) opioids released during NSSI regulate affect. These predictions are discussed in terms of previous models and other functions of NSSI.