Flashbacks to terrifying incidents can often make a person feel perplexed and horrified. There are people who continue re-experiencing such nightmares or bad memories,  i.e. post-traumatic stress disorder (PTSD). It is a chronic impairment disorder that arises following exposure to traumatic or exceptionally threatening events. It can make one feel powerless, frightened, intensely sad, and severely anxious. PTSD can take a heavy toll on a person’s health, livelihood, family life, and relationships. (https://onlinelibrary.wiley.com/doi/10.1002/wps.20656)

PTSD leads to problems with concentration and sleep, greater reactivity, petulance, more frequent startle reaction, etc. It also causes substantial dysfunction in occupational, social, and other life spheres. The treatment of choice for post-traumatic stress disorder is mainly cognitive behavior therapy (CBT) and antidepressants such as selective serotonin reuptake inhibitors (SSRIs). Managing this disorder is a hard nut to crack.

In recent times, marijuana has been shown to help in reducing the symptoms of PTSD.

A study has found that marijuana can improve anxiety, improve sleep, diminish nightmares and sleep disturbances, and also reduce other complaints related to sleep. (https://www.jpn.ca/content/44/2/75)

There is no cure for PTSD, but marijuana has been shown to provide some relief of symptoms.(https://www.sciencedirect.com/science/article/apii/S0165032720306364?via%3Dihub)