The human body contains a complex system called the Endocannabinoid System (ECS) which is involved in regulating sleep, pain, appetite, mood and immune system response. The body produces endocannabinoids, which are the neurotransmitters, or brain hormones, whose proteins bind to cannabinoid receptors in the nervous system. CBD helps to correct the lower amounts of this neurotransmitter in PTSD, specifically the CB1 receptor site.