Sleep restriction performance

Rogers, P. J., Heatherley, S. V., Hayward, R. C. et al. (2005). Effects of caffeine and caffeine withdrawal on mood and cognitive performance degraded by sleep restriction. Psychopharmacology 179 (4), 742-52. 

Chronic partial sleep restriction is a topic of current interest and one that was examined two decades ago by Carskadon and Dement (18). During a week of restriction to 5 hr of sleep a night, 10 college-aged adults manifested an accumulating decrease of sleep latency scores that did not plateau. A more recent chronic sleep restriction study (34) showed a. 95 correlation of performance measures with the Carskadon and Dement MSLT scores. These studies provided important support for the concept of sleep deficits that continue to grow as sleep reduction is prolonged. A more recent interpretation implicates excess wake as the primary factor rather than sleep deficit (35). 

Dinges DF, Pack F, Williams K, Gillen KA, Powell JW, Ott GE, Aptowicz C, Pack AI. Cumulative sleepiness, mood disturbance, and psychomotor vigilance performance decrements during a week of sleep restricted to 4—5 hours per night. Sleep 1997 20(4) 267-277. 

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.)...

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. 

In an earlier experiment, cumulative increases in PVT lapses across 7 days of sleep restricted to approximately 5 hr per night (29) were shown to be strongly related (r = -0.95) to sleep onset latency as assessed by the Multiple Sleep Latency Test (MSLT) in a nearly identical protocol (72). It appears that PVT performance lapse frequency and the well-validated physiological measure of sleep propensity may reflect the same basic process of escalating sleep pressure with sleep loss. 

Belenky G, Wesensten NJ, Thorne DR, Thomas ML, Sing HC, Redmond DP, Russo MB, Balkin TJ. Patterns of performance degradation and restoration during sleep restriction and subsequent recovery a sleep-dose response study. J Sleep Res 2003 12 1-12. 

The effect of sleep loss associated with medical disorders can manifest in several ways. Several studies have reported on the detrimental effects of sleep restriction on neurobehavioral functioning. Following only one night of restricted sleep decreased neurobehavioral performance and increased subjective sleepiness and sleep propensity have been reported (1). When the number of nights of sleep restriction is extended beyond one, cumulative decrements in neurobehavioral functioning (2,3) and increased daytime sleepiness levels are evident (4). 

Carskadon MA, Roth T. Sleep restriction. In Monk TH, ed. Sleep, Sleepiness and Performance. New York Wiley, 1991 155-67. 

A creative series of studies found that young adult volunteers could reduce their habitual sleep from 8 hr to about 5 hr with almost undetectable effects on performance or mood, except for an increase in sleepiness (42,43). Such investigations should be repeated and expanded, to see if such sleep restriction is so free of morbid risk. 

Until recently, it has been assumed that the performance effects of chronic sleep restriction were a milder version of the effects of acute, total sleep deprivation and that recovery from both was rapid once normal amounts of sleep were restored. Results from a study recently completed in our laboratory suggest that this may not be the case. 

In a sleep dose-response study (3,8) we examined the effects of three conditions of sleep restriction [3, 5, or 7 hr time in bed (TIB)] and one condition of sleep augmentation (9 hr TIB) on performance over 7 days and during the subsequent 3 days of recovery (all groups = 8 hr TIB). These sleep dose-response effects were compared against the training/baseline period in which all groups were allowed 8 hr TIB. 

Figure 1 Effect of sleep restriction on performance and subsequent recovery. (Adapted from Belenky et al. 2003.)...

The pattern of adaptation to chronic sleep restriction punctuated with acute, total sleep deprivation and rapid recovery from the latter may yield the types of changes in performance depicted in Fig. 2. Across the three armed services, in combat operations and in training for combat operations, severe total sleep deprivation is rare. Much more common for all is chronic, moderate sleep restriction at levels that would be expected to produce stable, albeit degraded performance. 

Finally, there is what can be best termed a folk belief, held by a number of military personnel, that high motivation as well as the excitement and adrenaline produced by a high-operational tempo can keep soldiers performing even in the face of severe sleep restriction/deprivation. However, motivation has been shown to be ineffective in sustaining performance (44 see also Chap. 21). Anecdotal accounts of combat indicate that the effects of adrenaline release are short-lived and are followed by extreme fatigue and sleepiness (45). 

A later study supported the findings that methylphenidate s benefits are most apparent in sleep-deprived/sleep-restricted volunteers. Roehrs et al. (52) compared the effects of 09 00 doses of 10 mg methylphenidate to placebo on sleepiness (Multiple Sleep Latency Test, MSLT), Profile of Mood States (POMS) ratings, and divided-attention performance after either 4 or 8 hr of sleep. After these test days, the 4- and 8-hr sleep conditions were repeated, but this time subjects were given their choice of drug or placebo. Results indicated that performance was improved by methylphenidate, most notably after the 4-hr condition. Methylphenidate also improved sleep latency and mood, but only after restricted sleep. During the choice phase of the study, subjects showed a preference for methylphenidate after 4 hr sleep (in 88% of opportunities), but not after 8 hr sleep (in only 29% of opportunities), suggesting that the preference for methylphenidate depended on the perceived sleepiness level of the individual. 

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