Circadian Rhythms, Sleep Deprivation, and Human Performance - Progress in Molecular Biology and Translational Science - page 170

propensity increase with sleep deprivation. Sleep deprivation affects a wide
range of cognitive domains (including attention, working memory, abstrac-
tion, and decision making) and results in decreases in both the encoding of
new information and memory consolidation. 165 Vigilant attention perfor-
mance and psychomotor speed, as assessed with the PVT, are affected early
and progressively more severely by sleep deprivation. 86,166 Although
sustained attention seems a prerequisite for high levels of performance on
more complex cognitive tasks, several studies have shown that the latter
are less affected by sleep loss than attention, probably because they are more
challenging and engaging than sustained attention tasks that unmask fatigue
by their limited evocation of additional neural processing areas. 39,167 In
addition, some of the differences among tasks in sensitivity to sleep depriva-
tion may be explained by practice effects confounding the effects of sleep
deprivation on more complex tasks. At the same time, the ability of stimu-
lants to counteract the effects of sleep deprivation seems to depend on the
cognitive domain studied. 168
The neurobehavioral effects of chronic sleep restriction are less severe
than those observed after acute total sleep deprivation, but the former can
reach levels of deficit equivalent to total sleep loss when the sleep restriction
is severe enough (i.e., the consecutive days of restricted sleep continue long
enough). 10,32 Chronic sleep-restriction experiments suggest that the neuro-
biology underlying the neurobehavioral deficits can continue to undergo
long-term changes. This is supported by a study investigating recovery after
a period of chronic sleep restriction that suggests a single recovery night of
up to 10 h time in bed is insufficient for some behavioral functions to return
to prerestriction levels. 33 Evidence of longer time constants in homeostatic
sleep pressure manifesting in waking neurobehavioral

functions was

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reported by Rupp et al. who varied the amount of baseline nightly sleep

prior to chronic sleep restriction and found that it affected both the rate at
which alertness was degraded and the rate at which deficits were reversed by
repeated nights of recovery sleep.

6.1. Phenotypic and genotypic differences in response to
sleep deprivation
We have repeatedly demonstrated that there are large and highly replicable,
trait-like individual differences in the magnitude of fatigue, sleepiness, sleep
homeostatic, and cognitive performance vulnerability to acute total sleep
deprivation 170,171 and to chronic sleep restriction. 32,148,172,173 Some indi-
viduals are highly vulnerable to neurobehavioral performance deficits when