Recurrent +Gz-induced loss of consciousness.

G-LOC--+Gz-induced loss of consciousness--results in significant acute incapacitation, including a period of unconsciousness lasting approximately 15 s followed by an additional period of approximately 15 s of confusion and disorientation. During routine experimentation for other purposes, four individuals experienced recurrent (3-5) episodes of G-LOC over 6-15 min. While G-LOC was neither an intended nor a desired event, we acknowledged the difficulty of stopping very high onset +Gz (VHOG) runs rapidly enough on the basis of visual endpoints to avoid occasional G-LOCs, which occurred in this limited series of experiments at a greater rate than in our more typical protocols. The requirement to define physiologic responses of fliers to operationally-relavent VHOG profiles made the development of these data pertinent and necessary. The recurrent G-LOC episodes accentuated the psychologic reactions experienced by the subjects, and allowed detailed analysis. Three of the individuals underwent detailed psychiatric interrogation to define the resultant G-LOC reactions. In addition to the post-G-LOC difficulty in recognizing the unconsciousness episode due to amnesia, specific psychologic reactions such as suppression (denial) further complicate one's ability to recognize the episode. G-LOC episodes may also lead to a reduction in combat readiness and aggressive capability in aerial combat. Recovery from G-LOC occurs in phases characterized by specific psychologic factors. The major psychologic reactions following G-LOC include confusion, disorientation, suppression of G-LOC recognition, unreliability, altered judgment, embarrassment, dissociation, euphoria, anxiety, fear, antagonism, and a "give-up" attitude.(ABSTRACT TRUNCATED AT 250 WORDS)