(paraphrased from Fowler & Fowler) hyper: a prefix meaning excessively, above normal. Thus, to be alert or aroused beyond normal limits.

Mental and physical changes in the central and peripheral nervous system activation to perceived or actual threat, including increased sensory and perceptual focus on the threat, activation of physiological systems required for survival and corresponding changes in emotional and behavioral functioning.

A state or condition of muscular and emotional tension produced by hormones released during the fight-or-flight reaction.