ABSTRACT
PURPOSE: The study aimed to evaluate the possible influence of prolonged sleep deprivation on achromatic and chromatic (red-green and blue-yellow) contrast sensitivity (CS). METHODS: During 60-hr sleep deprivation, CS was measured in 11 naval officers every sixth hour using videographic (Vigra-C) sine-wave-generated stimuli. RESULTS: When comparing the CS measurements obtained in the first and last 24 hr of the study, no statistically significant mean changes of achromatic CS (2.0, 5.9 and 11.8 cpd) or yellow-blue CS (0.6, 2.0 and 4.7 cpd) were found, while a significantly increased mean red-green CS at 2.0 and 4.7 cpd was recorded in the last 24 hr (p = 0.003 in both). The variance of achromatic and chromatic CS measurements in the group did not differ significantly in the first and last 24 hr test periods. CONCLUSIONS: Prolonged sleep deprivation does apparently not cause clinically or occupationally significant changes of contrast sensitivity in otherwise healthy subjects with normal visual acuity.
Subject(s)
Color Vision/physiology , Contrast Sensitivity/physiology , Sleep Deprivation/physiopathology , Adult , Evoked Potentials, Visual , Humans , Male , Military Personnel , Norway , Ocular Physiological Phenomena , Time Factors , Vision Tests/methods , Visual Acuity , Young AdultABSTRACT
This study investigated how workload and performance in high-speed ship navigation was affected by sleep deprivation using methods based on either paper charts or electronic chart display and information systems (ECDIS). In two separate weeks, five navigators sailed 10 routes in high-fidelity simulators while undergoing progressive sleep deprivation for up to 60 h. Results showed that navigation performance was better using ECDIS, but was largely unaffected by sleep deprivation in both. There was significant interaction between speed, sleep deprivation and navigation method, indicating that navigators using ECDIS reduced their speed more while sleepy. Secondary task performance was reduced by sleep deprivation, but was equally affected in both conditions. Workload was higher in the ECDIS condition, as indicated by subjective ratings and heart rate variability. No significant differences in sleepiness were found, but electroencephalographic recordings indicated more frequent microsleep episodes in the ECDIS condition. This may be influenced by lower overall arousal while navigating with ECDIS.
Subject(s)
Acceleration , Attention , Decision Making , Executive Function , Military Personnel/psychology , Naval Medicine , Posture , Problem Solving , Psychomotor Performance , Ships , Sleep Deprivation/psychology , Adult , Computer Simulation , Humans , Male , Norway , Orientation , Safety , Theta Rhythm , Workload/psychology , Young AdultABSTRACT
This study examines mental workload and performance in simulated high-speed ship navigation. Two navigation methods were compared based on an electronic chart display and information system (ECDIS) and a conventional system using paper charts. Twenty naval cadets navigated in high-fidelity simulators through a 50 nautical mile course with varying levels of difficulty. Results showed that ECDIS navigation significantly improved course-keeping performance, but reduced the total amount of communication on the bridge. No differences were observed in subjective workload between groups. Heart rate variability and skin conductance measurements indicated higher workload in conventional navigation, but the differences between groups were not significant.
