Is sleep‐related verbal memory consolidation impaired in sleepwalkers?

Abstract

SUMMARYIn order to evaluate verbal memory consolidation during sleep in subjects experiencing sleepwalking or sleep terror, 19 patients experiencing sleepwalking/sleep terror and 19 controls performed two verbal memory tasks (16-word list from the Free and Cued Selective Reminding Test, and a 220-and 263-word modified story recall test) in the evening, followed by nocturnal video polysomnography (n = 29) and morning recall (night-time consolidation after 14 h, n = 38). The following morning, they were given a daytime learning task using the modified story recall test in reverse order, followed by an evening recall test after 9 h of wakefulness (daytime consolidation, n = 38). The patients experiencing sleepwalking/sleep terror exhibited more frequent awakenings during slow-wave sleep and longer wakefulness after sleep onset than the controls. Despite this reduction in sleep quality among sleepwalking/ sleep terror patients, they improved their scores on the verbal tests the morning after sleep compared with the previous evening (+16 AE 33%) equally well as the controls (+2 AE 13%). The performance of both groups worsened during the daytime in the absence of sleep (À16 AE 15% for the sleepwalking/sleep terror group and À14 AE 11% for the control group). There was no significant correlation between the rate of memory consolidation and any of the sleep measures. Seven patients experiencing sleepwalking also sleep-talked during slow-wave sleep, but their sentences were unrelated to the tests or the list of words learned during the evening. In conclusion, the alteration of slow-wave sleep during sleepwalking/sleep terror does not noticeably impact on sleep-related verbal memory consolidation.

Memory consolidation in sleep disorders

“…Using a similar experimental design, the same researchers investigated overnight declarative memory consolidation in 19 patients (M age ¼ 30 y) with sleepwalking (n ¼ 16) or sleep terror (n ¼ 3) compared to 19 controls (M age ¼ 32 y) [79]. Although the group of patients showed a more fragmented SWS than controls, both groups exhibited an overnight consolidation effect, improving their performance in both the verbal tests used from the evening to the morning session.…”

Sleep deprivation impairs inhibitory control during wakefulness in adult sleepwalkers

“…This finding further supports the idea that sleepwalking includes measurable daytime consequences and suggests that these manifestations are observable more readily after sleep deprivation. Daytime cognitive functioning in sleepwalkers was studied recently under normal daytime conditions and yielded negative results (Uguccioni et al ., ). However, the authors examined only verbal learning and sleep‐related episodic memory consolidation, and studies have yet to investigate sleepwalkers' daytime cognitive functioning following sleep deprivation.…”

Disorders of Arousal

“…Surprisingly, they reported the case of a sleepwalker who re-enacted the motor sequence of the learned task during an episode. On the contrary, in the study of Uguccioni et al [39], 7 patients showed episode of sleeptalking during the recording nights but the content of the sentences was not related to the list of words of the task.…”

“…As SWS activity is known to be strongly associated to memory consolidation [38], a possible negative effect of these disorders on memory function is arguable. Uguccioni et al [39] tested verbal memory consolidation during sleep in patients affected by SW and ST. Two verbal memory tasks were employed in order to assess memory consolidation across the night. Furthermore, a learning task was used during the day to test consolidation after 9 h of wakefulness.…”