If you are experiencing nightmares while taking Trintellix, there are a few things you can try to improve your sleep. You may want to speak to your pharmacist or doctor about potentially adjusting your dosage or trying a different time of day to take the medication. Additionally, practicing good sleep hygiene, such as maintaining a consistent sleep schedule, creating a relaxing bedtime routine, and avoiding screens before bed, may help improve your sleep quality. If the issue persists or becomes too bothersome, it is important to discuss it with a healthcare professional for further guidance.