Seasonal pattern of posttraumatic stress disorder admissions.

Seasonal influences in some psychiatric disorders have been reported. Therefore, we examined whether a seasonal variation exists in posttraumatic stress disorder (PTSD). Charts of Vietnam veterans with PTSD (N = 160) admitted to a Veterans Administration Medical Center during a 3-year period were reviewed for season of admission. We found that admissions for PTSD were significantly more frequent in spring and summer. These preliminary results suggest the possibility that seasonal factors may influence PTSD.