Estimating that people sleep on average up to two hours less over the last decades, sleepiness and fatigue need to be considered as significant societal problems of the modern world. Jurisdiction is precise on how to deal with overtired offenders since they were not allowed to use machines or vehicles in the first place, similar to drunk individuals or consumers of illicit drugs. In contrast to alcohol or illicit drug use, however, there are no quick roadside or workplace tests as objective (analytical) biomarkers for sleepiness. Investigators hypothesize that increasing sleep drive or impaired wakefulness can be assessed by qualitative or quantitative fluctuations of certain metabolites in biological specimens, e.g., accumulation or decrease of endogenous substances related to sleep debt. Thus, this sleep study provides the necessary biological samples of either sleep-deprived, sleep-restricted, or control subjects, which are then analysed for appropriate metabolite biomarkers utilizing an untargeted metabolomics approach. In addition to established impairment tests, a state of the art driving simulator will be employed to objectively measure driving performance under all study conditions. Participants will also rate their subjective sleepiness using validated questionnaires.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
29
Total sleep deficit of consecutive 8 hours
Total sleep deficit of cumulative 8 hours
Human Sleep Laboratory, University of Zurich
Zurich, Canton of Zurich, Switzerland
Changes in metabolite concentrations in oral fluid quantified by liquid chromatography with mass spectrometry
Investigators will collect oral fluid samples from participants for quantification of all detectable metabolites. Investigators will analyze which metabolite concentration values undergo significant changes during sleep deficit conditions in comparison to control condition and also show effects of recovery sleep. These will serve as candidate biomarkers.
Time frame: After arrival at study site (6pm, baseline), repeatedly during scheduled wakefulness (8am, 12pm, 4pm, 7pm, 11pm), and morning after recovery night of 8 hours of sleep (8am)
Driving performance
Investigators will gather driving simulation results via Standardized Application for Fitness to Drive Evaluations (S.A.F.E. scale), and analyze their changes after sleep deficit in comparison to control condition. This scale has a range from 0 (best) to 10 (worst) in full steps.
Time frame: morning after experimental night (10am)
Psychomotor Vigilance Test
The Psychomotor Vigilance Test is a gold standard reaction time test to assess vigilance and sustained attention.
Time frame: After arrival at study site (6pm, baseline), repeatedly during scheduled wakefulness (8am, 12pm, 4pm, 7pm, 11pm), and morning after recovery night of 8 hours of sleep (8am)
d2 Test of Attention
The d2 Test of Attention is a paper and pencil test to assess selective and sustained attention and visual scanning speed.
Time frame: After arrival at study site (6pm, baseline), repeatedly during scheduled wakefulness (8am, 12pm, 4pm, 7pm, 11pm), and morning after recovery night of 8 hours of sleep (8am)
Visual attention test
The visual attention test is a virtual reality glasses test to assess visual skills in a complex visual environment.
Time frame: After arrival at study site (8pm, baseline), repeatedly during scheduled wakefulness (10am, 2pm, 6pm, 8pm), and morning after recovery night of 8 hours of sleep (8am)
Subjective situational sleepiness
Participants will complete the Karolinska Sleepiness Scale questionnaire.
Time frame: After arrival at study site (6pm, baseline), repeatedly during scheduled wakefulness (8am, 12pm, 4pm, 7pm, 11pm), and morning after recovery night of 8 hours of sleep (8am)
Subjective sleepiness
Participants will complete the Stanford Sleepiness Scale questionnaire.
Time frame: After arrival at study site (6pm, baseline), repeatedly during scheduled wakefulness (8am, 12pm, 4pm, 7pm, 11pm), and morning after recovery night of 8 hours of sleep (8am)
Electroencephalographic changes
Investigators will analyze changes in sleep and wake electroencephalographic patterns of participants by calculating sleep scores according to American Academy of Sleep Medicine (AASM) scoring manual.
Time frame: During scheduled sleep, driving simulation test (10am), and at two time points during scheduled wakefulness (12pm, 7pm)
Behavioral markers of drowsy driving
Investigators will examine participants after driving simulation test for behavioral abnormalities concerning orientation, coordination, speech, mood, appearance, reaction, and pupillary light reflex.
Time frame: Once per study arm after driving simulation test (11am)
Changes in metabolite concentrations in exhaled breath quantified by liquid chromatography with mass spectrometry
Investigators will collect exhaled breath samples from participants for quantification of all detectable metabolites. Investigators will analyze which metabolite concentration values undergo significant changes during sleep deficit conditions in comparison to control condition and also show effects of recovery sleep. These will serve as secondary candidate biomarkers.
Time frame: After arrival at study site (8pm, baseline), repeatedly during scheduled wakefulness (10am, 2pm, 6pm, 8pm, 11pm), and morning after recovery night of 8 hours of sleep (8am)
Changes in metabolite concentrations in finger sweat quantified by liquid chromatography with mass spectrometry
Investigators will collect finger sweat samples from participants for quantification of all detectable metabolites. Investigators will analyze which metabolite concentration values undergo significant changes during sleep deficit conditions in comparison to control condition and also show effects of recovery sleep. These will serve as secondary candidate biomarkers.
Time frame: After arrival at study site (8pm, baseline), repeatedly during scheduled wakefulness (10am, 2pm, 6pm, 8pm, 11pm), and morning after recovery night of 8 hours of sleep (8am)
Correlation of metabolic changes between blood and non-invasive specimens
Investigators will compare metabolite concentrations in non-invasive matrices (oral fluid, finger sweat, exhaled breath, and dried blood spots) and compare those with blood sample.
Time frame: immediately after driving simulation test (11am)
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