Previous studies have established a bidirectional relationship between sleep and pain, and mood has been proposed as a mediator of this relationship. There are only a limited number of longitudinal studies examining the mediational role of mood, and the directionality of effects between sleep, pain, and mood is uncertain. In addition, despite the high prevalence of pain and sleep problems during adolescence, these relationships have rarely been examined in a longitudinal sample of adolescents. Here, longitudinal survey data with 5 yearly measurements were used to examine the bidirectional relationship between insomnia symptoms and pain across adolescence (M-baseline age = 13.65 years, N-baseline = 2767). We also explored if depressed mood, positive affect, and anxious mood are mediators in both directions of the sleep-pain relationship. Using latent variables for insomnia, pain, and mood at multiple time points, the data were analyzed with cross-lagged panel models for longitudinal data with structural equation modeling. Current results confirmed a bidirectional relationship between insomnia symptoms and pain, where the effect of insomnia symptoms on pain was stronger than vice versa. Depressed mood and anxious mood mediated the effect of insomnia symptoms on pain, but not the reverse effect of pain on insomnia symptoms. Positive affect did not serve as a mediator in either direction. These findings add novel insights into the temporal directionality of sleep, pain, and mood during adolescence, suggesting a temporal path from sleep to pain, through mood, rather than a reciprocal relationship between the constructs.