<unk>  is the physiological and psychological state of being awoken or of sense organs stimulated to a point of perception. It involves activation of the ascending reticular activating system (ARAS) in the brain, which mediates wakefulness, the autonomic nervous system, and the endocrine system, leading to increased heart rate and blood pressure and a condition of sensory alertness, desire, mobility, and readiness to respond.<unk>  is mediated by several neural systems. Wakefulness is regulated by the ARAS, which is composed of projections from five major neurotransmitter systems that originate in the brainstem and form connections extending throughout the cortex; activity within the ARAS is regulated by neurons that release the neurotransmitters acetylcholine, norepinephrine, dopamine, histamine, and serotonin. Activation of these neurons produces an increase in cortical activity and subsequently alertness.<unk>  is important in regulating consciousness, attention, alertness, and information processing. It is crucial for motivating certain behaviours, such as mobility, the pursuit of nutrition, the fight-or-flight response and sexual activity (the<unk>  phase of Masters and Johnson's human sexual response cycle). It holds significance within emotion and has been included in theories such as the James-Lange theory of emotion. According to Hans Eysenck, differences in baseline<unk>  level lead people to be extraverts or introverts. The Yerkes-Dodson law states that an optimal level of<unk>  for performance exists, and too little or too much<unk>  can adversely affect task performance. One interpretation of the Yerkes-Dodson Law is the Easterbrook cue-utilisation hypothesis. Easterbrook states that an increase of<unk>  decreases the number.
Arousal
Psychodynamics
Face
Gaze 
Face time
Seizure threshold
Acoustic reflex
Mental state