Insomnia symptoms following acquired brain injury are serious and common, associated with cognitive and emotional complaints. This systematic review aims to summarize and appraise the current knowledge regarding the efficacy of non-pharmacological treatments for insomnia after traumatic brain injury and stroke in adults. A systematic search in the electronic databases of Medline, PsycINFO and Embase was conducted on January 15, 2019. The search strategy included traumatic brain injury or stroke and a combination of keywords and Boolean operators to represent the concept of insomnia. Articles were restricted to those in English and study populations of human adults. A total of 4341 studies were found, of which 16 were included, representing seven different non-pharmacological treatments. While the quality and quantity of the studies does not allow for firm conclusions, the outcomes suggest that cognitive behavioural therapy improves insomnia and sleep quality. The results highlight the need for larger studies of better methodological quality on non-pharmacological interventions for insomnia following brain injury.