Sleep Deprivation Reveals Altered Brain Perfusion Patterns in Somnambulism.

BACKGROUND: Despite its high prevalence, relatively little is known about the pathophysiology of somnambulism. Increasing evidence indicates that somnambulism is associated with functional abnormalities during wakefulness and that sleep deprivation constitutes an important drive that facilitates sleepwalking in predisposed patients. Here, we studied the neural mechanisms associated with somnambulism using Single Photon Emission Computed Tomography (SPECT) with 99mTc-Ethylene Cysteinate Dimer (ECD), during wakefulness and after sleep deprivation. METHODS: Ten adult sleepwalkers and twelve controls with normal sleep were scanned using 99mTc-ECD SPECT in morning wakefulness after a full night of sleep. Eight of the sleepwalkers and nine of the controls were also scanned during wakefulness after a night of total sleep deprivation. Between-group comparisons of regional cerebral blood flow (rCBF) were performed to characterize brain activity patterns during wakefulness in sleepwalkers. RESULTS: During wakefulness following a night of total sleep deprivation, rCBF was decreased bilaterally in the inferior temporal gyrus in sleepwalkers compared to controls. CONCLUSIONS: Functional neural abnormalities can be observed during wakefulness in somnambulism, particularly after sleep deprivation and in the inferior temporal cortex. Sleep deprivation thus not only facilitates the occurrence of sleepwalking episodes, but also uncovers patterns of neural dysfunction that characterize sleepwalkers during wakefulness.

Sleep deprivation impairs inhibitory control during wakefulness in adult sleepwalkers.

Sleepwalkers often complain of excessive daytime somnolence. Although excessive daytime somnolence has been associated with cognitive impairment in several sleep disorders, very few data exist concerning sleepwalking. This study aimed to investigate daytime cognitive functioning in adults diagnosed with idiopathic sleepwalking. Fifteen sleepwalkers and 15 matched controls were administered the Continuous Performance Test and Stroop Colour-Word Test in the morning after an overnight polysomnographic assessment. Participants were tested a week later on the same neuropsychological battery, but after 25 h of sleep deprivation, a procedure known to precipitate sleepwalking episodes during subsequent recovery sleep. There were no significant differences between sleepwalkers and controls on any of the cognitive tests administered under normal waking conditions. Testing following sleep deprivation revealed significant impairment in sleepwalkers' executive functions related to inhibitory control, as they made more errors than controls on the Stroop Colour-Word Test and more commission errors on the Continuous Performance Test. Sleepwalkers' scores on measures of executive functions were not associated with self-reported sleepiness or indices of sleep fragmentation from baseline polysomnographic recordings. The results support the idea that sleepwalking involves daytime consequences and suggest that these may also include cognitive impairments in the form of disrupted inhibitory control following sleep deprivation. These disruptions may represent a daytime expression of sleepwalking's pathophysiological mechanisms.

Psychopathologic correlates of adult sleepwalking.

OBJECTIVES: Sleepwalking (SW) often has been associated with psychopathology, but the nature and magnitude of this relation remains unclear. The aim of our study was to investigate the presence of psychopathology in a large cohort of sleepwalkers and to determine if levels of psychopathology showed differential relations to specific characteristics of the disorder, including clinical history. METHODS: One-hundred and five sleepwalkers (39 men, 66 women; mean age, 32.4±9.5years) referred to our sleep disorders clinic for chronic SW underwent a comprehensive clinical investigation that included an overnight polysomnography (PSG) assessment in 90% of cases. All participants also completed a series of questionnaires, including the Beck Depression Inventory, Second Revision (BDI-II), the Beck Anxiety Inventory (BAI), and the Symptom Checklist 90-Revised (SCL-90-R). RESULTS: The proportion of sleepwalkers who scored above the minimal clinical threshold on the BDI-II, BAI, and SCL-90-R was 27%, 40%, and 28%, respectively. Only 15% of sleepwalkers showed moderate to severe symptoms on the BDI-II and 19% on the BAI. Taken as a whole, these profiles are similar to those observed in the general adult population. The presence of psychopathology in sleepwalkers was associated with a negative family history for SW, a higher frequency of nightmares, and with potentially injurious behaviors enacted during somnambulistic episodes. CONCLUSIONS: A majority of adult sleepwalkers consulting for the disorder do not report clinically significant levels of depression or anxiety. Overall, sleepwalkers with and without psychopathology appear more similar than dissimilar.

Daytime somnolence in adult sleepwalkers.

OBJECTIVES: Sleepwalkers often complain of excessive daytime somnolence (EDS). Our retrospective study aimed to document the presence of EDS in a substantial sample of sleepwalkers and to explore the contribution of other sleep disorders, nocturnal sleep disruption, and sleep depth to the alteration of their daytime vigilance. METHODS: Seventy adult sleepwalkers and 70 control subjects completed the Epworth Sleepiness Scale (ESS). Sleepwalkers also were studied for one night in the sleep laboratory. We compared the sleep profiles of 32 somnolent vs 38 nonsomnolent sleepwalkers and investigated the relationship between ESS scores and sleep-related variables. RESULTS: No differences were found in polysomnographic (PSG) parameters. Slow-wave activity (SWA) also was similar in the two subgroups. Sleepwalkers' ESS scores were not correlated with their body mass index (BMI) or periodic limb movements during sleep (PLMS) index, but they tended to be negatively correlated with indices of respiratory events. CONCLUSIONS: The EDS reported by adult sleepwalkers does not appear to be explained by the presence of concomitant sleep disorders or PSG signs of nocturnal sleep disruption. These results raise the possibility that EDS is part of the sleepwalking phenotype and that it is linked to its underlying pathophysiology.