Sleep-to-wake transition movement disorders.

Consciousness and vigilance level are important factors for the manifestation and variability of many disorders, including movement disorders. Usually lumped together into unspecified "Wakefulness," the transition between wakefulness and sleep--the pre-dormitum, and between sleep and wakefulness--the post-dormitum, possess intrinsic cerebral metabolic patterns and mental, behavioural, and neurophysiological characteristics which make these peculiar states of vigilance independent. Moreover, the pre- and post-dormitum, with the relative state-dependent changes in firing patterns of many neuronal supra-pinal populations, act to release pacemakers responsible for different sleep-related motor phenomena. The relevance of pre-dormitum and post-dormitum as states different from full wakefulness and full sleep is, indeed, indicated by disorders which appear exclusively during either state, including motor disorders such as propriospinal myoclonus and awakening epilepsy. We will focus on three paradigmatic physiological/pathological motor phenomena (rhythmic movement disorder, hypnic jerks, and propriospinal myoclonus) strictly linked to the sleep-wake transition periods. Thereafter we will briefly discuss how the process of pre-dormitum and post-dormitum can lead to such disruption of motor control.