I have insomnia from Clarkia and last night mixed valerian root, skullcap and passion flower and slept much better. Took 2 capsules one hour before retiring. Also, feel much better today. This mixture would probably help your nightmares. Also, might consider lowering dose but lowest dose of Clarkia caused me insomnia. In addition, tried adjusting doses into 2 and not taking any in evening but still did not sleep. Therefore, will continue with this mixture. Alternate with catnip tea. Sleep very important for restoration.
Valerian root is primary sedative and used when sleep disorders are the result of anxiety, nervousness, exhaustion, headache or hysteria. Also used to treat tachycardia.
Skullcap numbs pain that might prevent falling asleep.
Passion Flower used to induce relaxation and sleep.