Previous research has demonstrated that sleep disturbances are positively correlated with sensory sensitivities in children with ASD. Most of these studies, however, were based on cross-sectional analyses, where the relationship across symptom domains was examined at a single time-point. Here, we examined the development of 103 pre-school children with ASD over a 1-3-year period. The results revealed that spontaneous longitudinal changes in sleep disturbances were specifically correlated with changes in sensory sensitivities and not with changes in other sensory processing domains nor with changes in core ASD symptoms. These finding demonstrate a consistent longitudinal relationship between sleep disturbances and sensory sensitivities, which suggests that these symptoms may be generated by common or interacting underlying physiological mechanisms.