Sleep deprivation conditions

Figure 4 PVT performance responses to varying doses of daily sleep. Mean PVT lapses per day (07 30-23 30), measured at 2-hr intervals, expressed relative to baseline (BL), in subjects randomized to an 8-hr (n = 9 open diamond), 6-hr (n = 13 open square), or 4-hr (n = 13 open circle) sleep opportunity per day for 14 consecutive days or 0-hr (n = 13 closed square) sleep condition across 3 days. The curves represent statistical nonlinear model-based best-fitting profiles of the PVT performance response to sleep loss. The mean ( s.e.m.) ranges of neurobehavioral functions for 1 and 2 days of total sleep deprivation (0 hr sleep) are illustrated by the light and dark bands, respectively, allowing comparison of the 3-day total sleep deprivation condition and the 14-day chronic sleep restriction conditions. (From Ref. 35.)...

A number of studies have investigated subjective sleepiness under sleep deprivation conditions. A study on the effects of partial sleep deprivation found that subjective sleepiness increased as the sleep deprivation period progressed across 5 consecutive days (31). Other studies have also found that sleepiness increased during different lengths of sleep deprivation and varied by time of day,... 

The relationship between subjective sleepiness and performance is only one method of examining potential relationships between how individuals perceive the effects of sleep deprivation on their ability to function. Another method is to examine how capable sleep-deprived individuals are of self-monitoring their level of performance. As with subjective sleepiness, the ability to accurately monitor performance under sleep-deprived conditions is an important issue for many workers in our society. Unfortunately, few studies have addressed this particular topic. 

Of interest for this chapter, however, is the ability of individuals to accurately assess their internal state of motivation during sleep deprivation conditions. Unfortunately, research in the sleep deprivation field has not yet addressed this issue. It would seem that questions assessing individuals motivation to complete a task might be related to, yet different from, their subjective assessment of effort. Future studies could be designed to investigate the relationship between sleep deprivation and motivation to complete a task and the relationship of motivation to subjective effort. 

Bishop C, Roehrs T, Rosenthal L, Roth T. Alerting effects of methylphenidate under basal and sleep-deprived conditions. Exp Clin Psychopharmacol 1997 5(4) 344-352. 

Naitoh et al. (45) employed a sleep/wake schedule of 20-min naps every 6 hr during a 64-hr period of continuous work, comparing this experimental condition against a second condition comprising total sleep deprivation for the entire 64-hr period. Compared to the sleep deprivation condition, the 20-min naps significantly reduced the cumulative effects of sleep loss on a four-choice reaction time task. 

In conditions of acute sleep deprivation, "microsleeps" will occur more and more often. These very short sleeps do not have the recuperative value of normal sleep, and the sleep-deprived person still feels sleepy and performance still degrades even though there may be a large number of microsleep periods. 

Most sleep deprivation experiments have used mentally and physically healthy young adults. For other types of individuals, particularly older people for whom the sleep function deteriorates in general, and also for "real world" conditions, sleep deprivation may be more significant. 

Treuer, K. von, Norman, T. R. 8r Armstrong, S. M. (1996). Overnight human plasma melatonin, cortisol, prolactin, TSH, under conditions of normal sleep, sleep deprivation, and sleep recovery. J. Pineal Res. 20, 714. 

We don t know the basis of this loss of temperature control, but we do know that REM sleep is itself associated with failure of the central thermostat, and we know that REM sleep deprivation also causes a loss of temperature. A unifying hypothesis is that any condition that potentiates REM sleep physiology may also compromise the central regulation of body temperature. Relevant to this hypothesis is the fact that the two brain stem aminergic neuromodulators that are inactivated in REM sleep are active in responding to thermal stress. 

The underlying assumption of the MSLT is that lower scores indicate greater sleepiness and vice versa. A common rubric holds that a daily average score of less than 5 min indicates a pathological level of daytime sleepiness. This level is associated with impaired performance in patients and in sleep-deprived normal subjects (26). Scores of adult normal controls usually range from 10 to 20 min (27). Scores between 5 and 10 min indicate moderate sleepiness, and may or may not be associated with pathological conditions (23). 

The MSLT is the most common method of objectively measuring daytime sleepiness in sleep laboratories. This test has been standardized into a form that reliably measures sleepiness in various populations. The MSLT has been used to evaluate levels of sleepiness (1) in conditions of sleep deprivation, reduction, fragmentation, and extension (2) in suspected narcoleptic patients (3) in patients with various disorders of excessive daytime sleepiness (4) in patients with insomnia and (5) in the posttreatment condition of patients with sleep disorders associated with daytime sleepiness. Further work is needed to compare subjective measures of sleepiness and newer performance measures with the MSLT. 

A wide variety of tests have been used in sleep deprivation experiments ranging from simple tests of reaction time (e.g., Refs. 1,2,13) to complex tasks of higher-order cognitive capacity and PFC function (e.g., Refs. 9,14,15). The diversity of performance tests available for use in performance testing leads to a fundamental question What are the criteria for an effective neurocognitive assay under conditions of sleep deprivation, where effective means theoretically meaningful, empirically sensitive, and practically useful ... 

Moreover, daily PVT lapse rates increased at a more rapid rate in the reduced sleep conditions. Figure 4 displays the results from the first of these studies, in which subjects were restricted to 4, 6, or 8-hr time in bed for sleep for 14 consecutive days (35). The results were compared to 88 hr of total sleep deprivation. Figure 4 illustrates the dose-response relationship between sleep opportunity and the degree of impairment in PVT performance. Interestingly, this cumulative impairment was found to be almost linear for lapse rates. Further, subjects randomized to the 4- and 6-hr sleep restriction conditions reached levels of impairment equivalent to those of subjects undergoing 1-2 nights of total sleep deprivation. 

Interventions such as naps and caffeine to counteract the neurobehavioral effects of sleep loss and sleepiness in healthy adults have been found to improve PVT performance (73-77). The PVT has been successfully used to track the effects of napping in laboratory (77) and operational (31) settings. The use of naps in the laboratory to augment the performance of sleep-deprived subjects is illustrated in the control condition of Figure 3, which shows that PVT errors of omission and commission during 88 hr of sleep deprivation are substantially reduced by 2-hour naps taken every 12 hr. 

Medical conditions based in nearly all physiological systems can produce coincident sleep disturbances and sleep deprivation. This includes disorders of the cardiovascular (chronic heart failure), pulmonary (asthma), gastrointestinal (hepatic failure), renal (urinary tract infections, polyuria), endocrine (diabetes, hypothyroidism, hyperthyroidism), and neurological (Parkinson s disease,... 

II. Impact of Sleep Deprivation Associated with Medical Conditions and/or Diseases... 

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