Showing papers by "Mathias Basner published in 2011"

Maximizing sensitivity of the psychomotor vigilance test (PVT) to sleep loss.

Abstract: STUDY OBJECTIVES The psychomotor vigilance test (PVT) is among the most widely used measures of behavioral alertness, but there is large variation among published studies in PVT performance outcomes and test durations. To promote standardization of the PVT and increase its sensitivity and specificity to sleep loss, we determined PVT metrics and task durations that optimally discriminated sleep deprived subjects from alert subjects. DESIGN Repeated-measures experiments involving 10-min PVT assessments every 2 h across both acute total sleep deprivation (TSD) and 5 days of chronic partial sleep deprivation (PSD). SETTING Controlled laboratory environment. PARTICIPANTS 74 healthy subjects (34 female), aged 22-45 years. INTERVENTIONS TSD experiment involving 33 h awake (N = 31 subjects) and a PSD experiment involving 5 nights of 4 h time in bed (N = 43 subjects). MEASUREMENTS AND RESULTS In a paired t-test paradigm and for both TSD and PSD, effect sizes of 10 different PVT performance outcomes were calculated. Effect sizes were high for both TSD (1.59-1.94) and PSD (0.88-1.21) for PVT metrics related to lapses and to measures of psychomotor speed, i.e., mean 1/RT (response time) and mean slowest 10% 1/RT. In contrast, PVT mean and median RT outcomes scored low to moderate effect sizes influenced by extreme values. Analyses facilitating only portions of the full 10-min PVT indicated that for some outcomes, high effect sizes could be achieved with PVT durations considerably shorter than 10 min, although metrics involving lapses seemed to profit from longer test durations in TSD. CONCLUSIONS Due to their superior conceptual and statistical properties and high sensitivity to sleep deprivation, metrics involving response speed and lapses should be considered primary outcomes for the 10-min PVT. In contrast, PVT mean and median metrics, which are among the most widely used outcomes, should be avoided as primary measures of alertness. Our analyses also suggest that some shorter-duration PVT versions may be sensitive to sleep loss, depending on the outcome variable selected, although this will need to be confirmed in comparative analyses of separate duration versions of the PVT. Using both sensitive PVT metrics and optimal test durations maximizes the sensitivity of the PVT to sleep loss and therefore potentially decreases the sample size needed to detect the same neurobehavioral deficit. We propose criteria to better standardize the 10-min PVT and facilitate between-study comparisons and meta-analyses.

Single and combined effects of air, road, and rail traffic noise on sleep and recuperation.

Abstract: Study Objectives: Traffic noise disturbs sleep and may impair recuperation. There is limited information on single and combined effects of air, road and rail traffic noise on sleep and recuperation. Design: Repeated measures Setting: Polysomnographic laboratory study Participants: 72 healthy subjects, mean ± standard deviation 40 ± 13 years, range 18-71 years, 32 male Interventions: Exposure to 40, 80, or 120 rail, road, and/or air traffic noise events Measurements and Results: Subjects were investigated for 11 consecutive nights, which included eight noise exposure nights and one noise-free control night. Noise effects on sleep structure and continuity were subtle, even in nights with combined exposure, most likely due to habituation and an increase in arousal thresholds both within and across nights. However, cardiac arousals did not habituate across nights. Noise exposure significantly affected subjective assessments of sleep quality and recuperation, whereas objective performance was unaffected, except for a small increase in mean PVT reaction time (+4 ms, adjusted P 3 kHz) noise event components. Conclusions: Road, rail, and air traffic noise differentially affect objective and subjective assessments of sleep. Differences in the degree of noise-induced sleep fragmentation between traffic modes were explained by the specific spectral and temporal composition of noise events, indicating potential targets for active and passive noise control. Field studies are needed to validate our findings in a setting with higher ecologic validity.

Fitness for duty: a 3-minute version of the Psychomotor Vigilance Test predicts fatigue-related declines in luggage-screening performance.

Abstract: Objective: To evaluate the ability of a 3-minute Psychomotor Vigilance Test (PVT) to predict fatigue-related performance decrements on a simulated luggage-screening task (SLST). Methods: Thirty-six healthy nonprofessional subjects (mean age = 30.8 years, 20 women) participated in a 4-day laboratory protocol including a 34-hour period of total sleep deprivation with PVT and SLST testing every 2 hours. Results: Eleven and 20 lapses (355-ms threshold) on the PVT optimally divided SLST performance into high-, medium-, and low-performance bouts with significantly decreasing threat detection performance A′. Assignment to the different SLST performance groups replicated homeostatic and circadian patterns during total sleep deprivation. Conclusions: The 3-minute PVT was able to predict performance on a simulated luggage-screening task. Fitness-for-duty feasibility should now be tested in professional screeners and operational environments.

Impact of nocturnal railway and aircraft noise on awakening probability in the field

Abstract: Introduction: Surveys suggest that - at the same noise level - railway noise is less annoying than aircraft or road traffic noise. Thus, railway noise is less strongly regulated in some European countries. However, in a laboratory study performed at the DLR-Institute of Aerospace Medicine railway noise lead to higher degrees of sleep fragmentation than aircraft noise. Our objective was to compare reactions to aircraft and railway noise in the field. Methods: In a field study on railway noise, 33 healthy participants (mean age 36.2 years ± 10.3 (SD); 22 females) were examined during nine consecutive nights. Polysomnography and noise events were recorded during every night. In total, 8866 railway noise events were used for analysis of noise-induced awakenings. In a field study on aircraft noise, data from 64 subjects and 10658 noise events were recorded. The datasets from rail and aircraft noise were pooled to facilitate a direct comparison. Results: In agreement with former studies, macrostructure of sleep was only slightly altered by noise. Awakening probability (sleep stage changes to wake/S1) due to railway noise increased significantly from 6.5% at 35 dB(A) to 20.5% at 80 dB(A) maximum sound pressure level (p<0.0001). In the comparison of traffic noise sources, awakening probability decreased in the order freight train noise, aircraft noise, and passenger train noise. Different reaction probabilities were explained amongst others by the sound pressure rise time of the noise event. Conclusions: In contrast to the results of annoyance surveys, nocturnal freight train noise lead to significantly increased awakening probabilities that exceeded those observed for aircraft noise at the same maximum sound pressure level. In line with our laboratory findings these awakening probabilities were higher than for aircraft noise. Freight wagons that are technically outdated or more developed may result in different physiological reaction probabilities.