The impact of acute stress and trauma on mental health can be important and associated with development of disorders such as posttraumatic stress disorder, complex posttraumatic stress disorder, prolonged grief disorder, and reactive attachment disorder. Stress and trauma disorders can lead to harmful changes in the brain and cognitive functions, often resulting in changes to specific brain circuits and networks. Also, these disorders can influence the autonomic system interfering with the release and uptake of neurotransmitters in the synaptic cleft. The first line of treatment includes psychotropic drugs and psychotherapy. However, a significant portion of affected individuals do not reply to the first line of treatment, requiring other approaches. In this chapter, alternatives such as non-invasive brain stimulation, mainly repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and vagal and trigeminal stimulation, will be presented as safe and promising options to treat these disorders.