Modafinil is an alerting substance that is considered safer than amphetamine with fewer side effects. Although modafinil has been used successfully to treat narcolepsy, relatively little is known about its ability to ameliorate fatigue and declines in mental performance due to sleep deprivation (SD) in a normal population. Forty-one military subjects received either 300 mg of modafinil, 20 mg of d-amphetamine, or placebo on 3 separate occasions during 64 hours of continuous cognitive work and sleep loss. Three drug treatments were given: at 23.30 hours and 05.30 hours during the first and second SD nights, respectively, and once at 15.30 hours during the third day of continuous work. Subjective estimates of mood, fatigue and sleepiness, as well as objective measures of reaction time, logical reasoning and short-term memory clearly showed better performance with both modafinil and amphetamine relative to placebo. Both modafinil and amphetamine maintained or increased body temperature compared to the natural circadian cycle observed in the placebo group. Also, from subject debriefs at the end of the study, modafinil elicited fewer side-effects than amphetamine, although more than the placebo group. Modafinil appears to be a good alternative to amphetamine for counteracting the debilitating mood and cognitive effects of sleep loss during sustained operations.

Self-monitoring refers to the ability to assess accurately one's own performance in a specific environment. The present study investigated the effects of the stimulating drugs modafinil (300 mg) and d-amphetamine (20 mg) on the ability to self-monitor cognitive performance during 64 h of sleep deprivation (SD) and sustained mental work. Two cognitive tasks were investigated: a visual (perceptual) judgment task and a complex mental addition task. Subjects in the placebo condition displayed marked circadian and SD effects on cognitive task performance but their self-monitoring was substantively undisturbed by SD. Subjects performing under the influence of damphetamine likewise displayed highly proficient self-monitoring throughout the SD period. In contrast, modafinil had a disruptive effect on self-monitoring, inducing a reliable 'overconfidence' effect (i.e. an overestimation of actual cognitive performance), which was particularly marked 2-4 h post-dose. Although modafinil has proven to be a safe and effective countermeasure to the effects of extensive SD on cognitive task performance, we encourage a more comprehensive understanding of the relation between its subjective and performance enhancing effects before the drug is recommended as a viable fatigue countermeasure.

The stimulant modafinil has proved to be an effective treatment modality for narcolepsy and related sleep disorders and is also being studied for use during sustained military operations to ameliorate the effects of fatigue due to sleep loss. However, a previous study reported that a relatively large, single dose of modafinil (300 mg), administered to already sleep-deprived individuals, caused participants to overestimate their cognitive abilities (i.e. 'overconfidence'). Because the predominant application of modafinil is in otherwise healthy, non-sleep-deprived individuals, the present study investigated the generality of modafinil-induced overconfidence in a group of 18 healthy, non sleep-deprived adults. The design involved a double-blind, placebo controlled, fully within-subjects manipulation of placebo and modafinil (4 mg/kg: approximately 300 mg, on average) over three 50-min cognitive testing sessions (i.e. before drug ingestion, and at 90 and 180 min after drug ingestion). The cognitive task battery included subjective assessments of mood, fatigue, affect, vigor and motivation, and cognitive assessments of serial reaction time, logical reasoning, visual comparison, mental addition and vigilance. In addition, trial-by-trial confidence judgements were obtained for two of the cognitive tasks and more global, task level assessments of performance were obtained for four of the cognitive tasks. Relative to placebo, modafinil improved fatigue levels, motivation, reaction time and vigilance. In terms of self-assessments of cognitive performance, both the placebo and modafinil conditions were 'well calibrated' on trial-by-trial confidence judgements, showing neither marked over- nor under-confidence. Of note, the modafinil condition displayed a non-significant tendency towards 'overconfidence' for task-level assessments of performance. The present findings highlight the need for continued research on the many complex interactions involving fatigue states, occasional versus long-term stimulant use, and subjective assessments of fatigue and cognitive performance.

This research was directed toward the contradiction sustained by cognitive dream psychology, which on the one hand regards dreaming as higher symbolic activity and, on the other, sees its organizational and functional characteristics as derivative and/or inferior to those of waking consciousness. Study 1 evaluates the degree of self-reflective meta-cognition in dreams from different sleep stages. Subjects were 24 college students selected such that half were self-reported high-frequency dream recallers and half were low-frequency recallers. Both groups were composed equally of men and women. Greater self-reflectiveness (SR) was found in REM dreams as compared with those from stages 2 and 4, which did not differ. High-frequency recallers showed more dream SR than did low-frequency recallers. Study 2 assessed the extent to which self-reflective and lucid dreaming can be learned as a cognitive skill by varying levels of intention and attention paid to dreaming. After 3 weeks of home dream collection, results showed that four experimental groups had greater dream SR than did a baseline group. The most effective treatment was the mnemonic, wherein attention patterning schemas learned in waking resulted in more self-reflective and lucid dreaming than did either baseline or attention-control conditions. These results provide evidence that dreaming is not single-minded but variable along a self-reflective process continuum, and suggest functional and organizational levels that are consistent with the conception of dreaming as higher order cognitive activity.

Polysomnograms were obtained from 37 volunteers, before (baseline) and after (two consecutive recovery nights) a 64-h sleep deprivation, with (d-amphetamine or modafinil) or without (placebo) alerting substances. The drugs were administered at 23.00 hours during the first sleep deprivation night (after 17.5 h of wakefulness), to determine whether decrements in cognitive performance would be prevented; at 05.30 hours during the second night of sleep deprivation (after 47.5 h of wakefulness), to see whether performance would be restored; and at 15.30 hours during the third day of continuous work, to study effects on recovery sleep. The second recovery night served to verify whether drug-induced sleep disturbances on the first recovery night would carry over to a second night of sleep. Recovery sleep for the placebo group was as expected: the debt in slow-wave sleep (SWS) and REM sleep was paid back during the first recovery night, the rebound in SWS occurring mainly during the first half of the night, and that of REM sleep being distributed evenly across REM sleep episodes. Recovery sleep for the amphetamine group was also consistent with previously published work: increased sleep latency and intrasleep wakefulness, decreased total sleep time and sleep efficiency, alterations in stage shifts, Stage 1, Stage 2 and SWS, and decreased REM sleep with a longer REM sleep latency. For this group, REM sleep rebound was observed only during the second recovery night. Results for the modafinil group exhibited decreased time in bed and sleep period time, suggesting a reduced requirement for recovery sleep than for the other two groups. This group showed fewer disturbances during the first recovery night than the amphetamine group. In particular, there was no REM sleep deficit, with longer REM sleep episodes and a shorter REM latency, and the REM sleep rebound was limited to the first REM sleep episode. The difference with the amphetamine group was also marked by less NREM sleep and Stage 2 and more SWS episodes. No REM sleep rebound occurred during the second recovery night, which barely differed from placebo. Hence, modafinil allowed for sleep to occur, displayed sleep patterns close to that of the placebo group, and decreased the need for a long recovery sleep usually taken to compensate for the lost sleep due to total sleep deprivation.

These findings demonstrate that the alertness-promoting effects of modafinil and d-amphetamine involve distinct EEG activities and do not reside on the same vigilance regulatory processes. While d-amphetamine inhibits the expression of a sleep-related process, probably through a direct cortical activation masking EEG circadian rhythms, modafinil, through a synchronic effect, preferentially disrupts the homeostatic down-regulation of a waking drive.

The issues and findings have implications for a wide range of distributed, collaborative work environments, such as military network-enabled operations.

The antagonistic effects of extensive sleep deprivation (SD) on human cognitive performance are well documented. However, one aspect of human performance that has not been investigated with respect to its susceptibility to SD is the 'meta-cognitive' ability to self-monitor overt performance. In the present study, 16 male subjects participated in an experiment requiring sustained cognitive work during a three day period. One of the cognitive tasks required the mental addition of rapidly presented numbers. On each trial, subjects reported the sum and then provided a subjective confidence rating to indicate the degree of certainty in their response. As expected, performance on the sequential addition task deteriorated with increasing fatigue and returned to baseline following a recovery sleep. However, calibration analyses, which quantify a number of properties of the relationship between subjective and overt performance, revealed that the correlation between confidence and performance (calibration), the ability to differentiate correct from incorrect judgments (resolution), and validity of subjective 'certainty', were all unaffected by SD. Hence, in the absence of external feedback from the environment, people have access to fairly reliable internal feedback about their performance during periods of sustained and vigilant cognitive activity.