UNASSIGNED: Appearances of alpha waves in the sleep electrencephalogram indicate physiological, brief states of awakening that lie in between wakefulness and sleep. These microstates may also cause the loss in @entity25 experienced by individuals suffering from @entity22 . To distinguish such pathological awakenings from physiological ones, differences in alpha-wave characteristics between transient awakening and wakefulness observed before the onset of sleep were studied. In polysomnographic datasets of sleep-healthy @entity1 (n  =  18) and @entity1 with @entity22 (n  =  10), alpha waves were extracted from the relaxed, wake state before sleep onset, wake after sleep-onset periods and arousals of sleep. In these, alpha frequency and variability were determined as the median and standard deviation of inverse peak-to-peak intervals. Before sleep onset, @entity1 with @entity22 showed a decreased alpha variability compared with healthy @entity1 (P  <  0.05). After sleep onset, both groups showed patterns of decreased alpha frequency that was lower for wake after sleep-onset periods of shorter duration. For @entity1 with @entity22 , alpha variability increased for short wake after sleep-onset periods. Major differences between the two groups were encountered during arousal. In particular, the alpha frequency in @entity1 with @entity22 rebounded to wake levels, while the frequency in healthy @entity1 remained at the reduced level of short wake after sleep-onset periods. Reductions in alpha frequency during wake after sleep-onset periods may be related to the microstate between sleep and wakefulness that was described for such brief awakenings. Reduced alpha variability before sleep may indicate a dysfunction of the alpha generation mechanism in @entity22 . Alpha characteristics may also prove valuable in the study of other @entity25 .

Alpha-wave frequency characteristics in health and XXXX during sleep.

@entity1 :: ('9606', 'Species') :: ['participants', 'patients'] @entity25 :: ('MESH:D012893', 'Disease') :: ['sleep quality', 'sleep and attention disorders'] @entity22 :: ('MESH:D007319', 'Disease') :: ['insomnia']
@entity22 :: (MESH:D007319,Disease) :: ['insomnia']
