莫达芬尼对48 h睡眠剥夺时视听运动反应和疲劳感的影响

目的 观察48h睡眠剥夺(sleep deprivation，SD)条件下正常人服用新型促醒剂莫达芬尼改善视听反应能力和疲劳感的效果。方法 6名健康男性青年志愿者，在2次SD实验(间隔2周)中交叉服用莫达芬尼和安慰剂，SD时间从第1天7：00至第3天7：00，于第2天0：00、16：00和第3天0：00分别服用莫达芬尼200mg或安慰剂，采用随机双盲给药，并在第1天21：00及每次服药后1h、3h、5h、7h各完成1次测试，内容包括：1)声、光刺激运动反应时；2)注意分配；3)临界闪光融合频率(critical flicker fusion frequency，CFF)；4)．斯坦福嗜睡量表(stanford sleepiness scale，SSS)；5)自认疲劳分级表(rating of perceived exertion，RPE)。结果 与安慰剂组比较，第2、3次服用莫达芬尼后CFF值较安慰剂组明显升高，斯坦福量嗜睡表、RPE表分值较安慰剂组明显下降；声、光刺激运动反应时与注意分配无明显变化。结论 莫达芬尼能明显降低SD条件下的疲劳感和困倦程度。     

服用莫达非尼对48h睡眠剥夺条件下模拟飞行操作能力的影响

目的观察48h睡眠剥夺（sleep deprivation，SD）条件下正常人服用莫达非尼改善模拟器飞行操作能力的效果。方法以6名健康男性青年志愿者为对象，在间隔2周的两次48hSD（从第1天8：00至第3天8：00）实验中交叉服用莫达非尼和安慰剂（于实验第2天0：00、16：00和第3天0：00服用，每次200mg），于第1天21：00及每次服药后1h、3h、5h、7h进行J7-E模拟器飞行操作测试。结果安慰剂组的模拟器飞行成绩随SD时间延长逐渐下降，在第3天1：00—7：00的飞行成绩明显降低：操作错误随着SD延长而增加，在第3天1：00—7：00的出错次数增多，并且左上转弯和着陆阶段的操纵错误较多。与安慰剂组相比，莫达非尼组的飞行成绩在第3次服药后明显提高。莫达非尼组48h SD总的操作错误数较安慰剂组降低了19％，第3天1：00—7：00的错误数较安慰剂组降低了40％。结论服用莫达非尼明显改善48hSD条件下的模拟飞行操作能力，在SD复合生物节律的影响时药效更明显。     

服用莫达非尼对24 h睡眠剥夺条件下人前庭功能的影响

目的 观察24h睡眠剥夺（SD）条件下服用莫达非尼对正常人前庭功能的影响。方法 以8名健康男性青年志愿者为对象,在间隔1周的两次24h SD（从第1天8：00至第2天8：00）实验中交叉服用莫达非尼和安慰剂200mg（于第2天0：00服用）,于第1天21：00及服药后1h、3h、5h、7h进行前庭功能测定。结果 SD使伪随机扫视跟踪精确度明显下降、视前庭眼动反射（visual-vestibular optokinetic reflex,WOR）和视动眼震（optokinetic nystagmus,OKN）增益明显降低,特别是第2天1：00～5：00;与安慰剂组相比,莫达非尼组的OKN增益明显增加。安慰剂组和莫达非尼组的其它前庭功能指标无明显差异。结论 24hSD会影响正常人体的前庭功能,服用莫达非尼对其中的视动性眼震具有一定的改善作用。     

莫达非尼对睡眠剥夺汽车兵汽车驾驶能力和疲劳感的影响

目的 观察36 h睡眠剥夺（SD）条件下服用莫达非尼对汽车兵汽车驾驶能力和疲劳感的影响.方法 60名男性汽车兵随机分为安慰剂组和莫达非尼组（各组n=30）.试验第1日起床（6：00）后,36 h保持不睡眠,于当日夜间23：00、第2日5：00、11：00三次服用莫达非尼或安慰剂200 mg.于试验第1日8：30和14：30及用药后4个时刻（即试验第2日7：00、10：00、13：00、16：00）共完成6次驾驶任务.测定指标包括考核场汽车驾驶能力、视听反应能力和临界闪光融合频率（CFF）、斯坦福嗜睡量表和自认疲劳分级量表评分.结果 两组的汽车驾驶成绩和视听反应能力无明显差异.与安慰剂组相比,莫达非尼组的CFF明显增加、主观嗜睡和疲劳感显著降低. 结论 36 h SD条件下分次服用常规剂量的莫达非尼具有显著降低机体疲劳感的作用,且对汽车驾驶能力无明显不良影响.     

降压药对人体认知操作能力和主观嗜睡感的影响

目的评价服用4种降压药贝那普利、阿替洛尔、氨氯地平和氯沙坦对正常人中枢神经系统功能的影响.方法 8名健康青年男性志愿者,在6次试验（每次间隔1周）中交叉服用贝那普利10 mg、阿替洛尔100 mg、氨氯地平10 mg、氯沙坦100 mg、唑吡坦10 mg和安慰剂,采用随机双盲设计给药,分别在服药前4 h,服药后1、2、3、4、6、8和10 h各完成一次计算机控制的单双重任务（包括四数连加、心理运动及两者复合的双重任务）能力测试;同时观察主观嗜睡度的变化.用重复测量的方差分析比较不同药物和用药后不同时间的差别.结果与安慰剂相比,唑吡坦对中枢能力产生明显不良影响：心理运动能力呈下降趋势、双重任务正确率明显降低（P＜0.05）、主观嗜睡度显著增加（P＜0.05）,用药后约6 h恢复正常;但4种降压药对人体认知操作能力和主观嗜睡感均无明显不良影响.结论单次服用贝那普利10 mg、阿替洛尔100 mg、氨氯地平10 mg或氯沙坦100 mg对人体认知操作能力和主观嗜睡感无明显不良影响.     

催眠药扎来普隆、三唑仑、唑吡坦和佐匹克隆对认知操作能力影响的比较

目的 比较催眠药扎来普隆、三唑仑、唑吡坦和佐匹克隆对正常人认知操作能力的影响.方法 8名健康青年男性志愿者,在5次试验（每次间隔1周）中交叉服用扎来普隆10 mg、三唑仑0.25 mg、唑吡坦10 mg、佐匹克隆7.5 mg和安慰剂,采用随机双盲设计给药,分别在服药前4 h、服药后1、2、3、4、6、8、10 h各完成1次认知能力测试,同时观察药物不良反应.测试内容包括：①单双重任务能力（包括计算机控制的4数连加、心理运动能力及二者复合的双重任务）;②光刺激反应时及运动时;③临界闪光融合频率.用重复测量的方差分析比较不同药物和用药后不同时间认知能力的差别.结果 与安慰剂相比,扎来普隆对各项指标无明显不良影响;三唑仑使心理运动能力和临界闪光融合频率下降;唑吡坦和佐匹克隆明显降低心理运动能力、双重任务保持率和临界闪光融合频率.此外,佐匹克隆还显著降低双重任务正确率.用药后约6 h各组的认知能力恢复正常.结论 基于认知操作能力的影响评价,扎来普隆是4种短效催眠药中最安全的药物.     

服用三唑仑对汽车兵夜间睡眠质量和次日汽车驾驶能力的影响

目的 观察服用三唑仑对汽车兵夜间睡眠质量和次日汽车驾驶能力的影响,为今后在飞行人员中应用提供试验依据.方法 60名男性汽车兵随机分为安慰剂组和三唑仑组（各组n=30）.试验第1日8：30和14：30各完成1次考核场汽车驾驶任务,在夜间0：00两组分别服用药物（三唑仑0.25 mg或安慰剂）后睡眠5.5 h,于次日7：00、10：00、13：00和16：00（用药后7～16 h）完成4次相同的驾驶任务,测定指标包括：主观睡眠质量、斯坦福嗜睡量表和自认疲劳分级量表评分,考核场汽车驾驶成绩,视听反应能力和临界闪光融合频率.结果 与安慰剂组相比,三唑仑组的主观睡眠质量明显提高,而汽车驾驶成绩、视听反应能力和闪光融合频率两组无明显差异.结论 常规单剂量服用三唑仑具有提高汽车兵睡眠质量的效果,用药7 h后对汽车驾驶能力无明显不良影响.     

咖啡因和三唑仑对人体科里奥利加速度耐力的影响

目的 探讨服用中枢兴奋药咖啡因及短效类催眠药三唑仑对人体科里奥利加速度耐力的影响。方法 8名健康青年男性志愿者,采用两阶段交叉设计方法,受试者随机分为两组,在5周内完成4次测试,每周1次,第3周受试者休息。受试者前两周于每周二8：00分别交叉服用咖啡因（200mg）和安慰剂各1次,每组服用咖啡因和安慰剂的先后顺序不同,在用药后1h进行科里奥利加速度耐力的检测;后两周于每周一24：00分别交叉服用三唑仑（0．25mg）和安慰剂各1次,每组受试者服用三唑仑和安慰剂的先后顺序不同,在用药8h后进行科里奥利加速度耐力的检测。结果 服用咖啡因（200mg)1h后及服用三唑仑（0．25mg)8h后受试者的科晨奥利加速度耐力值与安慰剂相比,差异无显著性意义。结论 服用中枢兴奋药咖啡因（200mg)1h后或服用短效类催眠药三唑仑（0．＝25mg)8h后人体抗晕机病能力未见明显变化。     

两种剂量水平的扎来普隆对正常人认知操作能力和前庭功能的影响

目的 比较两种剂量水平的扎来普隆对正常人认知操作能力和前庭功能的影响.方法 8名健康青年男性志愿者在3次试验(每次间隔1周)中交叉服用扎来普隆10 mg、15 mg和安慰剂,采用随机双盲设计给药,分别在服药前4 h、服药后1、2、3、4、6、8 h各完成一次认知能力测试,内容包括单双重任务(即计算机控制的四数连加、心理运动及二者复合的双重任务)能力;光刺激反应时及运动时;临界闪光融合频率(CFF).另6人参加前庭功能测评,试验设计与上述相同,测试内容包括视动眼震(OKN)、前庭眼动反射(VOR)、视前庭眼动反射(VVOR)和前庭眼动反射固视抑制(VOR-Fix).用重复测量的方差分析比较不同药物组和用药后不同时间观察指标的差别. 结果 与安慰剂组相比,两种剂量扎来普隆组的认知操作指标无明显变化,但OKN、VOR增益明显降低(F值分别为10.81、39.64,P＜0.05),用药后2～3 h恢复正常,其余前庭功能指标各组无明显差异.结论 服用扎来普隆10 mg和15 mg对认知操作能力无明显副作用,对前庭功能的轻度不良影响在用药3 h后恢复正常.     

持续认知操作活动诱发脑疲劳状态时服用酪氨酸的效果观察

目的 观察持续认知操作活动期间服用酪氨酸（Tyr)的效果。为飞行2中使用提供依据。方法 8名健康男性青年在22：00-06：00期间持续完成大约8h的方知操作任务和有关量表评定,02：00和03：00接受Tyr（或安慰剂）试验,04：00和05：00完成脑事件相关电位（ERPs)的测量。次日完成与残留效应有关的脑功能状态评定及肝、肾功能检查。结果 Tyr明显缩短ERPs的P3潜伏期并减缓认知操作反应错误率的上升趋势,同时也减轻了嗜眠及脑疲劳症状,服用Tyr对肝、肾功能及次日的工作影响均不显著。结论 Tyr在对抗持续认知操作活动期间的能力下降及改善脑功能状态方面可能是一种相对无害的物质,存在应用于飞行员的可能性。     

Modafinil vs. caffeine: effects on fatigue during sleep deprivation

INTRODUCTION: The extent to which modafinil and caffeine reverse fatigue effects (defined as performance decrements with time on task) during total sleep deprivation was investigated. METHODS: There were 50 healthy young adults who remained awake for 54.5 h (06:30 day 1 to 13:00 day 3). A 10-min vigilance test was administered bi-hourly from 08:00 day 1 until 22:00 day 2. At 23:55 day 2 (after 41.5 h awake), double-blind administration of one of five drug doses (placebo; modafinil 100, 200, or 400 mg; or caffeine 600 mg; n = 10 per group) was followed by hourly testing from 00:00 through 12:00 day 3. Response speed (reciprocal of reaction time) across the 10-min task (by 1-min block) was analyzed prior to and after drug administration. RESULTS: A fatigue effect (response speed degradation across the 10-min task) was exacerbated by sleep deprivation and circadian rhythmicity. Prior to the drug, this effect was maximal between 08:00 and 12:00 day 3 (24-28 h sleep deprivation). Modafinil 400 mg attenuated fatigue in a manner comparable to that seen with caffeine 600 mg; these effects were especially salient during the circadian nadir of performance (06:00 through 10:00); modafinil 200 mg also reversed fatigue, but for a shorter duration (3 min) than modafinil 400 mg (8 min) or caffeine 600 mg (6 min). DISCUSSION AND CONCLUSIONS: Time-on-task effects contributed to the performance degradation seen during sleep deprivation; effects which were reversed by caffeine and, at appropriate doses, by modafinil. Because the duration of efficacy for reversing time-on-task effects was shorter at lower drug dosages, the latter must be considered when determining the appropriate dose to use during sustained operations.     

Naps and modafinil as countermeasures for the effects of sleep deprivation on cognitive performance.

Disruptions in wake-sleep rhythms, particularly induced by sleep deprivation are limiting factors for military personnel in operations. The role of sleep and naps in the recovery of performance is generally accepted. Pharmacological aids, for example hypnotic or stimulant substances can also be effective countermeasures. Recently, a new stimulant compound, modafinil (MODIODAL) has also proven effective. Considering the excellent results obtained with napping and modafinil, we have studied the combined effect of these two countermeasures on psychomotor performance under conditions simulating an operational situation. Beneficial effects of a few hours' nap on performance were confirmed. Consequently naps should be encouraged, even if limited and diurnal. Modafinil, which combines wakening and stimulating properties without any known side effects, was useful for longer periods of sleep deprivation and when there was no real possibility of sleep recovery. Modafinil did not prevent sleep if sleep opportunities were available. The combination of naps and modafinil demonstrated the best cognitive performance during sleep deprivation.     

Caffeine improves physical performance during 24 h of active wakefulness

BACKGROUND: Reductions in both cognitive and physical performance occur during periods of sleep loss with sustained operations. It was the purpose of this study to examine the effects of caffeine on activities chosen to simulate the physical challenges that might occur during a military scenario involving a period of sleep loss. METHODS: There were 16 subjects (26.7 +/- 7.8 yr, 83.8 +/- 11.0 kg) who completed a double-blind caffeine and placebo trial involving a control day and sleep period followed by 28 h of sleep deprivation. A 400-mg dose of caffeine was administered at 21:30 followed by subsequent 100-mg doses at 03:00 and 05:00. At 22:00, subjects began a 2-h forced march followed by a sandbag piling task. A treadmill run to exhaustion at 85% of maximal aerobic power was performed at 07:00 of the second day of sleep deprivation. RESULTS: Caffeine had no effect on the heart rate or oxygen consumption, but rating of perceived exertion (RPE) was reduced with caffeine during the forced march. Time to complete the sandbag piling task during set 1 was significantly reduced with caffeine (12.9 +/- 1.0 min) compared with placebo (13.8 +/- 1.0 min) but there was no difference during set 2 and RPE was increased. Time to exhaustion was significantly increased 25% during the run with caffeine (17.0 +/- 4.4 min) compared with placebo (13.5 +/- 3.3 min), and caffeine maintained performance at control levels (16.9 +/- 4.6 min). CONCLUSIONS: It was concluded that caffeine is an effective strategy to maintain physical performance during an overnight period of sleep loss at levels comparable to the rested state.     

睡眠剥夺对工作绩效的影响

目的 探讨睡眠剥夺情况下人的工作绩效的变化规律。方法 8名健康青年作为被试,采用单因素区组化的实验设计方法。在实验日6：00至次日8：00的26h的持续觉醒过程中,每隔特定时间间隔重复一组相同的试验项目。测试项目：（1）听觉Oddball单任务反应时（RT1）和正确率（CR1）;（2）听觉Oddball 手控跟踪双任务的跟踪误差（ER）及反应时（RT2）和正确率（CR2）;（3）主观任务难度评价（SR）;（4）斯坦福困倦度量表（SSS）;结果RT1,RT2,ER 3项指标的9个时间点间整体比较均具有显著差异（分别为P＝0．0001,P＝0．0001,P＝0．0004）,3项指标在睡眠剥夺过程中均显著升高;睡眠剥夺对SR,SSS得分均具有显著影响（P＝0．0001,P＝0．0000）,在夜间这2项指标得分升高;由于反应策略的调整,被试的反应正确率在睡眠剥夺过程中无显著变化。结论 睡眠剥夺对认知反应任务反应时和跟踪任务的跟踪误差,主观任务难度评价及困倦程度均具有显著影响。     

Caffeine restores engagement speed but not shooting precision following 22 h of active wakefulness

BACKGROUND: Current military missions occasionally require combat readiness of soldiers who might be experiencing a sustained period of activity without sleep. Strategies to overcome the debilitating effects of sleep deprivation include the ingestion of caffeine. Unknown is the efficacy of caffeine use on specific elements of target detection and marksmanship following a modest period of sustained wakefulness. METHODS: There were 20 subjects (mean +/- SD of 26.7 +/- 7.2 yr of age, 179 +/- 6 cm in height, and 84.5 +/- 10.8 kg in weight) who participated in double-blind caffeine and placebo trials where each trial involved a 24-h control period (with sleep) followed by 22 h of mixed mental and physical activity with no sleep. At the end of this period, subjects engaged in a 1-h rifle-shooting task. Subjects ingested 400, 100, and 100 mg of caffeine or placebo at 7.5, 3, and 0 h, respectively, prior to shooting. Measures of shooting performance included target engagement time (between target appearance and firing), friend-foe discrimination, accuracy, and precision. RESULTS: Most measures of performance were degraded in the placebo sleep-deprived condition, but only the target engagement time and the number of shots fired were restored by caffeine ingestion. CONCLUSIONS: These findings concur with other research involving different periods of sleep deprivation, and indicate that the cognitive component of the shooting task (i.e., target detection) can benefit from caffeine whereas the psychomotor component (marksmanship) does not. It appears that once the target is detected, the subject is sufficiently aroused to engage the target regardless of the subject's level of alertness prior to detection.     

服用莫达非尼对雷达作业人员夜间作业能力的影响

目的 观察服用莫达非尼对雷达作业人员夜班作业能力的影响. 方法将值夜班(0:00～8:00)的20名男性雷达作业人员按随机数字表随机分为莫达非尼组和安慰剂组(每组n=10).于夜间2:00口服莫达非尼200 mg或安慰剂.在夜班前、后分别进行计算机模拟雷达信号及跟踪目标识别绩效、临界闪光融合频率(CFF)和数字划消成绩测试,夜班工作中对心电、心率等指标进行动态监测. 结果安慰剂组夜班后的CFF值(29.64±1.46)较夜班前(30.94±1.88)明显下降(t=5.87,P<0.01);莫达非尼组夜班后的CFF值(31.65±1.49)和数字划消总数(100.50±12.57)分别较夜班前(CFF值为29.85±2.65,数字划消总数为88.50±12.70)明显升高(t=5.94、14.54,P<0.05).与安慰剂组比较,莫达非尼组夜班后的数字划消总数和CFF值明显提高(t=2.70、2.73,P<0.05);莫达非尼组的心率、标化低频功率、低频与高频功率的比值增高,低频功率、高频功率、标化高频功率和总功率降低,相邻正常R-R间期差值的均方根值和极低频功率明显降低(t=2.41、2.37,P<0.05). 结论夜班作业时口服常规单剂量莫达非尼具有明显提高雷达操作能力和抗疲劳的效果.     

Melatonin and zopiclone as pharmacologic aids to facilitate crew rest.

PURPOSE: In response to mission imperatives, transport aircrews must often sleep at inappropriate circadian times resulting in inadequate sleep. This study was undertaken to determine whether either melatonin or zopiclone could facilitate early circadian sleep, and to assess whether either of these medications would result in a psychomotor performance decrement which would preclude their use in aircrew. METHOD: Thirteen subjects from DCIEM completed a double-blind cross-over protocol. All subjects were assessed for psychomotor performance during 3 drug conditions (placebo, 10 mg melatonin, and 7.5 mg zopiclone), which were separated by one week. Each of these conditions involved 2 nights of sleep, back-to-back, with the first night being a normal circadian control sleep (23:00 h bedtime, arising at 06:45 h), and the second night being an early circadian drug sleep (drugs at 16:45 h, 17:00 h bedtime, arising at 23:45 h). All subjects were tested for psychomotor performance, on both nights of each of the 3 drug conditions, pre- and post-sleep. Further, during the early circadian drug night, all subjects were tested every hour after arising at 23:45 h (24:00 h until 07:00 h. At the beginning of each psychomotor test session, subjects were asked for their subjective levels of sleepiness and fatigue. RESULTS: Relative to placebo (339.5 min) the subjects slept more on melatonin (370.2 min, p < 0.01), and zopiclone (373.3 min, p < 0.01). Performance in serial reaction time (SRT) task (p < 0.001), logical reasoning task (LRT) (p < 0.001), serial subtraction task (SST) (p < 0.02), and Multitask (MT) (p < 0.03) were impaired for all 3 drug conditions immediately on awakening, compared with pre-sleep performance, as a result of a sleep-inertia effect. With respect to the subjective data, sleep inertia effects were evident for sleepiness (p < 0.001), mental fatigue (p < 0.002), and physical fatigue (p < 0.05). For SRT, LRT, and SST, performance recovered to pre-sleep levels within 1.25 h of awakening, and for MT recovery occurred 2.25 h after awakening. There were no differences in performance or subjective measures between placebo, melatonin and zopiclone. CONCLUSIONS: Both zopiclone and melatonin improved sleep relative to placebo. After sleep inertia, performance recovered to pre-sleep levels for all tasks and was sustained at that level throughout the balance of the testing period. There was no impact of melatonin or zopiclone on performance measures compared with placebo.     

Modafinil's effects on simulator performance and mood in pilots during 37 h without sleep

INTRODUCTION: Modafinil is a relatively new alertness-enhancing compound of interest to the military aviation community. Although modafinil has been well-tested in clinical settings, additional studies are required to establish its safety and efficacy for use in pilots. OBJECTIVE: The purpose of this study was to determine whether modafinil (100 mg after 17, 22, and 27 h without sleep) would attenuate the effects of fatigue on fighter-pilot mood and performance during 37 h of continuous wakefulness. METHODS: A quasi-experimental, single-blind, counterbalanced design tested the effects of modafinil in 10 Air Force F-117 pilots. RESULTS: Modafinil attenuated flight performance decrements on six of eight simulator maneuvers. Overall, modafinil maintained flight accuracy within approximately 15-30% of baseline levels, whereas performance under the no-treatment/placebo condition declined by as much as 60-100%. Modafinil decreased self-ratings of depression and anger, while improving ratings of vigor, alertness, and confidence. Benefits were most noticeable after 24 to 32 h of continuous wakefulness. One potential drawback of modafinil was that, at least at the 100-mg dose level, the drug's effects were not subjectively salient. Since this may lead personnel to escalate the dose without flight surgeon approval, personnel should be cautioned regarding this particular drug characteristic. CONCLUSION: Although modafinil did not sustain performance at predeprivation levels, the present study suggests that modafinil should be considered for the military's armament of short-term fatigue countermeasures. Future research will evaluate whether 200-mg doses are more beneficial than the 100-mg doses used here.     

Restoration of risk-propensity during sleep deprivation: caffeine, dextroamphetamine, and modafinil

INTRODUCTION: Sleep deprivation alters risk-related judgments, decision-making, and behavioral control. Stimulant medications are used to restore cognitive performance, but their effects on risk-taking and judgment in sleep-deprived subjects have not been explored. METHODS: There were 54 healthy adults (29 men, 25 women; age range 18 to 36) who completed a test of cognitive ability and daily measures of risk-taking propensity, including the Brief Sensation Seeking Scale (BSSS), Evaluation of Risks (EVAR) scale, and the Balloon Analog RiskTask (BART). Following 44 h of continuous wakefulness, participants ingested caffeine 600 mg (N = 12), dextroamphetamine 20 mg (N = 16), modafinil 400 mg (N = 12), or a placebo (N = 14) in a double blind manner, and completed risk-taking measures 2 h later (i.e., 0535). RESULTS: Relative to rested baseline, the placebo group showed a decline in risk-taking as measured by the BSSS (16% decline), EVAR Danger Seeking (32% decline) and Energy (22% decline), and BART (32% decline), consistent with previous reports of the effects of sleep deprivation. Comparisons among drug conditions showed that dextroamphetamine restored risk-taking propensity and risky behavior to baseline levels, an effect that was significantly greater than placebo or caffeine for several indices of risk-taking, but which did not differ from modafinil. Cognitive ability was significantly correlated with changes on some risk-taking indices following stimulant administration. CONCLUSIONS: Stimulant medications, particularly dextroamphetamine, sustained risk-related attitudes and behavior during continuous wakefulness. The extent to which stimulants restore other aspects of judgment during sleep loss remains to be determined.