A Trial to See if Daridorexant Can Help Adults and Elderly People With Insomnia Sleep Better During the Night and Function Better During the Day

The purpose of this clinical trial is to collect more data about the effect of daridorexant in adults and elderly people with insomnia disorder. The trial aims to find out whether daridorexant can help improve: * how trial participants sleep at night, * how trial participants function the next day. Researchers will compare daridorexant to a placebo (a look-alike inactive substance that contains no active medicine) to understand which effect daridorexant has on total sleep time and next-day functioning. Enrolled participants will: * Take daridorexant 50 mg or placebo once daily for approximately 3 months * Visit the clinic once every month during treatment for checkups and tests * Keep a sleep diary of the number of hours they sleep and how well they sleep * Complete a questionnaire every day about any symptoms of sleepiness during the day and any impact on physical and mental functioning such as energy levels, mood, or ability to concentrate or memorize.