Arousal Levels

Acute exposure to caffeine raises arousal levels, subject to the inverted-U principle. 

One factor in the differential cognitive results may be baseline or prestimulation arousal level. When baseline arousal is already elevated, highly arousing tasks, such as those that are complex or involve intense stimuli, can result in overstimulation. As Hasenfratz and Battig49 note, it may be such excessive levels of stimulation that account for the commis-... 

Interestingly enough, most of the studies reporting positive effects of caffeine in information-processing tasks have used primarily or exclusively male subjects.39 42 43 45 48 59 In fact the only study that found positive cognitive effects of caffeine on females employed fatigued females, whose baseline arousal levels may have been lower.41... 

In addition to gender, task difficulty or complexity appears to be a substantial factor in arousal. Information processing tasks, particularly complex ones, have been shown to increase arousal levels in otherwise unstimulated subjects.60 The more complex the task, the higher the arousal level and the greater the chance that a given caffeine dosage would contribute to overstimulation. The additive nature of arousal sources — in this case caffeine and complexity — means that arousal is high when caffeine is present and complexity or difficulty level is substantial. The result is that caffeine impairs performance on complex tasks,50 51 particularly in female subjects. 

Anxiety is related to higher physiological and behavioral arousal levels,98-164 especially levels of affective arousal.185-188 Similarly, caffeine has... 

Parrott AC and Hindmarch I (1975). Arousal and performance - the ubiquitous inverted U relationship. Comparison of changes in response latency and arousal level in normal subjects induced by CNS stimulants, sedatives and tranquillizers. IRCS Medical Science, Clinical Pharmacology and Therapeutics, Psychiatry and Clinical Psychology, 3, 176. 

Initially, psychotropic drugs had focused mechanisms of action on levels of arousal and vigilance. Those drugs that depressed arousal levels were con-... 

The type of research described under this heading aims at correlating therapeutic outcome and pre-therapy sleep as well as therapy-induced sleep alterations. This section is voluntarily limited to the two therapies whose relationships to sleep are the most documented, i.e., antidepressant drugs and sleep deprivation therapy. The effects of these two therapies are examined in the light of the three theories. According to these theories, effective therapies have either to decrease the arousal level, to increase process S, or to restore the aminergic/cholinergic balance. 

Coull JT, Jones MEP, Egan TD, Frith CD, Maze M (2004) Attentional effects of noradrenaline vary with arousal level selective activation of thalamic pulvinar in humans. Neuroimage 22 315-322. 

There has been a clear military interest in manipulation of the noradrenaline neurotransmitter system in relation to the arousal level of the central nervous system for some time.8 That interest apparently continues one recent report suggesting that drugs affecting the system were appropriate for immediate consideration as a non-lethal technique. 9... 

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