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Hypoxia (HY) and sleep deprivation have opposite effects on appetite. As HY may alter sleep, it may be informative to assess the accumulative effects of these two stressors on hunger, energy intake (EI), and food reward. Seventeen young, active, healthy males completed four 5-hr sessions in normoxia (NO) or normobaric HY (FIO2 = 13.6%, ∼3,500 m) after a night of habitual sleep (HS; total sleep time >6 hr) or sleep restriction (SR; total sleep time <3 hr). Subjective appetite was assessed regularly using visual analogic scales and EI during an ad libitum lunch after 3.5 hr of exposure. Food reward was assessed using the Leeds Food Preference Questionnaire just before the lunch. As expected, EI was lower for the HY-HS (4.32 ± 0.71 MJ; p =.048) and HY-SR (4.16 ± 0.68 MJ, p =.013) sessions than the NO-HS (4.90 ± 0.84 MJ) session without acute mountain sickness-related gastrointestinal symptoms. No significant effect of SR alone was observed (NO-SR: 4.40 ± 0.68 MJ). Subjective appetite was not affected. Explicit liking for high-fat foods was higher with SR than HS (main effect: p =.002) and implicit wanting for high-fat foods was higher for the NO-SR, HY-HS, and HY-SR sessions than the NO-HS session (p <.006). Thus, acute SR did not modify subjective appetite or EI despite the increasing food reward for high-fat foods and did not alter the HY-induced changes of appetite or food reward. Hypoxia (HY; simulated real altitude) and sleep deprivation have opposite effects on appetite, the former decreases it while the latter increases it. As it is known that HY may alter sleep, it may be informative to assess the accumulative effects of these two stressors on hunger, energy intake (EI), and food reward. Seventeen young active, healthy males completed four 5-hr sessions in normoxia (NO) or normobaric HY (FIO2 = 13.6%, ∼3,500 m) after a night of habitual sleep (HS, TST >6 hr) or sleep restriction (SR, TST <3 hr). Hunger scores were assessed regularly using VAS and EI during an ad libitum lunch (beef ravioli, bread, and chocolate cream dessert) after 3.5 hr of exposure. The food reward for high-fat (compared with low-fat foods) and sweet (compared with savory foods) was assessed using the Leeds Food Preference Questionnaire just before lunch. As expected, EI was lower for the HY-HS (4.32 ± 0.71 MJ; p =.048) and HY-SR (4.16 ± 0.68 MJ, p =.013) sessions than the NO-HS (4.90 ± 0.84 MJ) session without acute mountain sickness-related gastrointestinal symptoms. Contrary to our hypothesis, no significant effect of SR alone was observed (NO-SR: 4.40 ± 0.68 MJ). Subjective appetite was not affected. Concerning food reward, explicit liking for high-fat foods increased with SR (main effect: p =.002) and implicit wanting for high-fat foods was higher for the NO-SR, HY-HS, and HY-SR sessions than the NO-SR session (p <.006). Thus, acute SR did not modify subjective appetite or EI despite the increasing food reward for high-fat foods and did not alter the HY-induced changes of appetite or food reward. It is possible that the absence of effects of SR was due the absence of choices during lunch. A meal or a snack with the option to select high-fat foods would have likely induced higher EI. Thus, in the limits of this study, a disturbed night inducing sleep deprivation seems to have no enhancing or limiting effect on the well-known HY-induced anorexia. Sleep deprivation lasting more than one night, with other levels of simulated or real altitude and the possibility to select different kind of foods based on its fat content may lead to different results. [ABSTRACT FROM AUTHOR]

Aircraft pilots face a high mental workload (MW) under environmental constraints induced by high altitude and sometimes sleep restriction (SR). Our aim was to assess the combined effects of hypoxia and sleep restriction on cognitive and physiological responses to different MW levels using the Multi-Attribute Test Battery (MATB)-II with an additional auditory Oddball-like task. Seventeen healthy subjects were subjected in random order to three 12-min periods of increased MW level (low, medium, and high): sleep restriction (SR, <3 h of total sleep time (TST)) vs. habitual sleep (HS, >6 h TST), hypoxia (HY, 2 h, FIO2 = 13.6%, ~3500 m vs. normoxia, NO, FIO2 = 21%). Following each MW level, participants completed the NASA-TLX subjective MW scale. Increasing MW decreases performance on the MATB-II Tracking task (p = 0.001, MW difficulty main effect) and increases NASA-TLX (p = 0.001). In the combined HY/SR condition, MATB-II performance was lower, and the NASA-TLX score was higher compared with the NO/HS condition, while no effect of hypoxia alone was observed. In the accuracy of the auditory task, there is a significant interaction between hypoxia and MW difficulty (F(2–176) = 3.14, p = 0.04), with lower values at high MW under hypoxic conditions. Breathing rate, pupil size, and amplitude of pupil dilation response (PDR) to auditory stimuli are associated with increased MW. These parameters are the best predictors of increased MW, independently of physiological constraints. Adding ECG, SpO2, or electrodermal conductance does not improve model performance. In conclusion, hypoxia and sleep restriction have an additive effect on MW. Physiological and electrophysiological responses must be taken into account when designing a MW predictive model and cross-validation. [ABSTRACT FROM AUTHOR]

Multi-Attribute Task Battery (MATB) is a computerized flight simulator for aviation-related tasks, suitable for non-pilots and available in many versions, including open source. MATB requires the individual or simultaneous execution of 4 sub-tasks: systemmonitoring (SYSMON), tracking (TRACK), communications (COMM), and resourcemanagement (RESMAN). Fully customizable, the design of test duration, number of sub-tasks used, event rates, response times and overlap, create different levels of mental load. MATB can be combined with an additional auditory attention (Oddball) task, or with physiological constraints (i.e., sleep loss, exercise, hypoxia). We aimed to assess the main characteristics of MATB design for assessing the response to different workload levels. We identified and reviewed 19 articles for which the effects of low and high workload were analyzed. Although MATB has shown promise in detecting performance degradation due to increase workload, studies have yielded conflicting or unclear results regarding MATB configurations. Increased event rates, number of sub-tasks (multitasking), and overlap are associated with increased perceived workload score (ex. NASA-TLX), decreased performance (especially tracking), and neurophysiological responses, while no effect of time-on-task is observed. The median duration used for the test is 20 min (range 12--60) with a level duration of 10 min (range 4--15). To assess mental workload, the median number of stimuli is respectively 3 events/min (range 0.6--17.2) for low, and 23.5 events/min (range 9--65) for high workload level. In this review, we give some recommendations for standardization of MATB design, configuration, description and training, in order to improve reproducibility and comparison between studies, a challenge for the future researches, as human-machine interaction and digital influx increase for pilots. We also open the discussion on the possible use of MATB in the context of aeronautical/operational constraints in order to assess the effects combined with changes in mental workload levels. Thus, with appropriate levels of difficulty, MATB can be used as a suitable simulation tool to study the effects of changes on the mental workload of aircraft pilots, during different operational and physiological constraints. [ABSTRACT FROM AUTHOR]

Hypoxia (HY) and sleep deprivation have opposite effects on appetite. As HY may alter sleep, it may be informative to assess the accumulative effects of these two stressors on hunger, energy intake (EI), and food reward. Seventeen young, active, healthy males completed four 5-hr sessions in normoxia (NO) or normobaric HY (FIO2 = 13.6%, ∼3,500 m) after a night of habitual sleep (HS; total sleep time >6 hr) or sleep restriction (SR; total sleep time <3 hr). Subjective appetite was assessed regularly using visual analogic scales and EI during an ad libitum lunch after 3.5 hr of exposure. Food reward was assessed using the Leeds Food Preference Questionnaire just before the lunch. As expected, EI was lower for the HY-HS (4.32 ± 0.71 MJ; p = .048) and HY-SR (4.16 ± 0.68 MJ, p = .013) sessions than the NO-HS (4.90 ± 0.84 MJ) session without acute mountain sickness-related gastrointestinal symptoms. No significant effect of SR alone was observed (NO-SR: 4.40 ± 0.68 MJ). Subjective appetite was not affected. Explicit liking for high-fat foods was higher with SR than HS (main effect: p = .002) and implicit wanting for high-fat foods was higher for the NO-SR, HY-HS, and HY-SR sessions than the NO-HS session (p < .006). Thus, acute SR did not modify subjective appetite or EI despite the increasing food reward for high-fat foods and did not alter the HY-induced changes of appetite or food reward.