Mindfulness-based interventions (MBI) have been shown to improve sleep quality among people with insomnia. However, much less is known about the effects of MBIs on other aspects of insomnia such as daytime symptoms and cognitive-emotional arousal. The purpose of this study was to examine the treatment effects on these domains for adults with chronic insomnia disorder who were randomized to mindfulness-based stress reduction (MBSR), mindfulness-based therapy for insomnia (MBTI), or a delayed-treatment control consisting of sleep diary self-monitoring (SM) followed by behavior therapy (BT). Analyses were conducted on baseline to post-treatment changes with superiority comparisons for each MBI to SM followed by non-inferiority comparisons for each MBI to BT. The results revealed significant reductions from baseline in the MBTI group with large effect sizes on sleep effort, maladaptive sleep-related cognitions, and hyperarousal which were superior to the SM control (p < 0.05) and non-inferior to BT (p < 0.025). MBSR demonstrated a significant increase in positive affect with a large effect size which was non-inferior to BT (p < 0.025) but not statistically significant compared to SM. These findings indicate that MBTI, a new MBI which combines mindfulness practices with behavioral sleep components, can be effective at reducing cognitive-emotional arousal related to insomnia while MBSR, a general MBI, can increase positive affect at a level similar to a standard behavioral treatment for insomnia.