RECENT PUBLICATIONS

Smith, M.E., McEvoy, L.K., & Gevins, A. (2002). The impact of moderate sleep loss on neurophysiologic signals during working memory task performance. Sleep, 25, 784-794.

ABSTRACT

Study Objectives: This study examined how sleep loss affects neurophysiological signals related to attention and working memory.
Design: Subjective sleepiness, resting-state EEG, and behavior and EEG during performance of working memory tasks, were recorded in a within-subject, repeated-measures design.
Setting: Data collection occurred in a computerized laboratory setting.
Participants: Sixteen healthy adults (mean age 26 years, 8 female) participated.
Interventions: Data from alert daytime baseline tests were compared with data from tests during a late night, extended wakefulness session that spanned up to 21 hours of sleep deprivation.
Measurements and Results: Alertness measured both subjectively and electrophysiologically decreased monotonically with increasing sleep deprivation. A lack of alertness-related changes in EEG measures of the overall mental effort exerted during task execution indicated that participants attempted to maintain high levels of performance throughout the late night tests. Despite such continued effort, responses became slower, more variable, and more error prone within one hour after participants' normal time of sleep onset. This behavioral failure was accompanied by significant degradation of event-related brain potentials related to the transient focusing of attention.
Conclusions: Moderate sleep loss compromises the function of neural circuits critical to sub-second attention allocation during working memory tasks, even when an effort is made to maintain wakefulness and performance. Multivariate analyses indicate that combinations of working memory-related behavioral and neurophysiological measures can be sensitive enough to permit reliable detection of such effects of sleep loss in individuals. Similar methods might prove useful for assessment of functional alertness in patients with sleep disorders.