The goal of this randomized controlled trial is to test the effectiveness of digital cognitive behavioral therapy for insomnia (dCBT-I) compared with digital patient education about insomnia for people with Multiple Sclerosis (MS). The main questions it aims to answer are whether dCBT-I is effective in reducing insomnia severity in people with MS, whether dCBT-I is effective in reducing daytime fatigue, psychological distress, cognitive problems, medication use (hypnotic, sedative/anxiolytic and antidepressant), resource utilization and if these changes are mediated by improvements in insomnia severity and whether dCBT-I is feasible for people with MS