Digitally provided psychological interventions for sleep disorders are currently a very intensively researched topic. In this review, original work and meta-analyses are summarized. Thus, it was shown that internet-based cognitive behavioral therapy for insomnia (CBT-I) in adults is consistently very effective, with only slightly reduced effects compared with the same treatment with the physical presence of therapists and patients. Treatment effects are also shown for secondary outcome parameters such as depression, anxiety, fatigue, and quality of life. On the other hand, research on the effectiveness of internet-based CGT‑I in adults with comorbid mental disorders or physical illnesses, and on the issue of how much contact with therapists should be integrated into treatment, does not seem to provide any conclusive answers. Further research seems to be needed in these areas.