Arousal

Arousal, is the English term for "arousal". Arousal is used in psychology, physiology and medicine (sleep medicine) and denotes the degree of activation of the central nervous system, which indicates alertness, attention and readiness to react of an organism.

The activation mechanism is triggered by impulses that are received via sensory or chemoreceptors and transmitted to the brain stem. The blood level of the hormone adrenaline is also involved in the excitation process. This increases body temperature, heart rate, blood pressure, gastrointestinal activity and perspiration.

The arousal can be measured by means of an electroencephalogram (EEG) and is quantified by the arousal index. Thus the arousal level is very low during sleep. In case of pain, fear, anger or sexual desire the arousal level is very high.

The connection between performance and arousal is made clear in the Yerkes-Dodson Law of 1908. According to this law, difficult tasks can be mastered up to a certain level of arousal. However, as the arousal level increases, the performance level decreases again; if there is continuous stress, fatigue and exhaustion can lead to a breakdown (distress).

In sleep medicine, "arousal" is a wake-up reaction with which the organism reacts to sleep apnea (see below sleep-related breathing disorders). This arousal reaction leads to a vital resumption of breathing. The whole body is activated and reacts with tachycardia, hypertension, increase in muscle tone. Furthermore, arousals can be triggered by external factors such as light, noise, etc. Also by internal stressors.