Hypervigilance is an enhanced state of sensory sensitivity accompanied by an exaggerated intensity of behaviors whose purpose is to detect threats. Hypervigilance is also accompanied by a state of increased anxiety which can cause exhaustion. Other symptoms include: abnormally increased arousal

Arousal

Arousal is a physiological and psychological state of being awake or reactive to stimuli. It involves the activation of the reticular activating system in the brain stem, the autonomic nervous system and the endocrine system, leading to increased heart rate and blood pressure and a condition of...

, a high responsiveness to stimuli

Stimulus (physiology)

In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....

, and a constant scanning of the environment for threats. Hypervigilance can be a symptom of posttraumatic stress disorder and various types of anxiety disorder

Anxiety disorder

Anxiety disorder is a blanket term covering several different forms of abnormal and pathological fear and anxiety. Conditions now considered anxiety disorders only came under the aegis of psychiatry at the end of the 19th century. Gelder, Mayou & Geddes explains that anxiety disorders are...

. It is distinguished from paranoia

Paranoia

Paranoia [] is a thought process believed to be heavily influenced by anxiety or fear, often to the point of irrationality and delusion. Paranoid thinking typically includes persecutory beliefs, or beliefs of conspiracy concerning a perceived threat towards oneself...

. Paranoid states, such as those in schizophrenia

Schizophrenia

Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

, can seem superficially similar, but are characteristically different.

Hypervigilance is differentiated from dysphoric hyperarousal in that the person remains cogent and aware of his or her surroundings. In dysphoric hyperarousal, the PTSD victim may lose contact with reality and re-experience the traumatic event verbatim. Where there have been multiple traumas, a person may become hypervigilant and suffer severe anxiety attacks intense enough to induce a delusional state where the effect of the traumas overlap: e.g., one remembered firefight may seem too much like another for the person to maintain calm. This can result in the thousand-yard stare

Thousand-yard stare

The thousand-yard stare or two-thousand-yard stare is a phrase originally coined to describe the limp, unfocused gaze of a battle-weary warrior...

.

Symptoms

People suffering from hypervigilance may become preoccupied with studying their environment for possible threats, causing them to lose connections with their family and friends. They will 'over-react' to loud and unexpected noises; become agitated in highly crowded or noisy environments etc. They will often have a difficult time getting to sleep or staying asleep.