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Introduction: The term arousal usually refers to transient, brief arousal during nocturnal sleep or to a state of vigilance which is maintained during the day., Development and Conclusion: In this review we consider the various accepted meanings and clinical disorders of 'arousal'. Insomnia (hyperarousal), parasomnias (partial arousal) and the sudden death syndrome of infancy are all attributed to disorders of arousal. It is concluded that diurnal hyperarousal leads to difficulty in getting off to sleep and staying asleep, whilst nocturnal arousal leads to excessive somnolence during the day, due to broken sleep during the night.

Introduction: The description of Upper Airway Resistance Syndrome (UARS) let us to recognize the importance of the pair 'respiratory effort-arousal' on sleep-disordered breathing pathophysiology., Development: First part of this paper reviews knowledge about respiratory arousal pathophysiology. Arousal response is normally needed to end obstructive respiratory episodes, but it is also the cause of sleep fragmentation. Among respiratory stimuli able to provoke arousal (respiratory effort, hypoxemia and hypercapnia), respiratory effort is the most constant. Neurophysiological mechanisms involved in arousal, sleep and vegetative consequences, and the possible role of non visible arousals, are also discussed. In UARS, because of the absence of apnea/hypopnea and significative O2 desaturations, arousals are induced by the increased respiratory effort. Diagnosis needs the simultaneous recording of polysomnography and esophageal pressure. Some symptoms and signs of UARS are similar to those of Obstructive Sleep Apnea Syndrome. However, UARS shows any differences: a lower Body Mass Index, less constant snoring, males and females are similarly affected or higher frequency of craniofacial abnormalities. Diagnostic difficulties may be due to confusion between hypopneas and episodes of increased resistance of upper airway, or to the lack of definitive diagnostic criteria. Finally, differential diagnosis needs a broad knowledge of disorders of excessive daytime sleepiness.

Objective: To describe different types of motor activity which occur during sleep in relation to episodes of arousal and sleep disorder., Development: During sleep, normal motor activity should be distinguished from paroxystic episodes: parasomnias; abnormal movements such as nocturnal paroxystic dystonia, which is very similar to epilepsy of frontal origin; nocturnal epileptic crises and especially periodic movements of the limbs and the restless legs syndrome, which is related to it. Physiological cyclical fluctuations of sleep are common to all these conditions and due to cortico-subcortical changes in excitability., Conclusion: We review diagnostic, clinical and neurophysiological criteria and aspects of physiopathology and treatment.