Just thinking about surgery can be a traumatic exercise for some people. However, the actual experience also carries its own risk of trauma. According to a new study from German researchers, a certain percentage of patients wake up during the course of their procedure, which can have long-term psychological consequences including the development of post traumatic stress disorder.

After examining the records of surgeries, researchers from Ruhr University found that about two out of every 1,000 patients wake up from anesthesia while doctors are still in the middle of the procedure.

Most often, this results from too little anesthesia. However, the researchers identified several other risk factors. These include a patient's misuse of painkillers, night-time surgery and patient age.

The researchers said that providing patients with ear plugs before going into surgery may reduce some of the risk of trauma in the event that they wake up during surgery. Additionally, seeking prompt treatment from drug rehab and mental health facilities may help reduce the chances of long-term effects from waking up during surgery.