Post-traumatic stress disorder, or PTSD, is an anxiety disorder that can develop after experiencing a traumatic event. Signs of PTSD include having unwanted, vivid recollections of the event and difficulty remaining calm. You may be irritable, have trouble sleeping, and constantly be watching or listening for danger.

Post-traumatic stress disorder, or PTSD, is an anxiety-based mental health condition brought on by experiencing a traumatic event.

Adrenaline is one of the body's most important stress chemicals. It is secreted from the adrenal glands, which sit atop each kidney. Adrenaline also plays a key role as a neurotransmitter that facilitates communication between brain cells, or neurons, and other cells.