Cannabis may help reduce the symptoms of post-traumatic stress disorder (PTSD) through two of its main cannabinoids, CBD and, to a lesser extent THC, with the aid of several terpenes. CBD interacts with several brain receptors – the cannabinoid type-1 receptor (CB1-R) and the serotonin receptor (5-HT1A). The interaction of CBD on these receptors can help to regulate fear and anxiety-related behaviors. This interaction is boosted by the Entourage Effect of the terpenes Limonene and Linalool, who on their own also possess the ability to reduce feelings of fear and anxiety. THC can help to reduce insomnia and the frequency of nightmares. Be aware however, that high levels of THC can, in some cases, cause heightened levels of anxiety.