This study will test a medicine called daridorexant to see if it helps people with Post-Traumatic Stress Disorder (PTSD). PTSD is a mental health condition that some people develop after experiencing or witnessing a traumatic event. The study is called a Phase 2 trial, which means researchers are checking if the medicine is safe and effective.

The trial is randomized, meaning participants are randomly assigned to take either the medicine or a placebo, which is a pill with no active ingredients. The study is also double-blinded, so neither the participants nor the researchers know who is getting the actual medicine, to ensure fair results.

Before joining, participants will be screened for 30 days. If eligible, they will be part of the study for 12 weeks and have a 4-week follow-up period to monitor any side effects. Participants should not have narcolepsy (a sleep disorder) or have taken daridorexant before.

• The study lasts about 16 weeks in total.
• Participants will be randomly assigned to receive either daridorexant or a placebo.
• Potential side effects will be monitored during the 4-week follow-up period.