An observational study in Drowsiness, Sleepiness and Fatigue, sponsored by University of Zurich. Completed at 1 site in Belgium. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-25.
Sponsored by University of Zurich · Observational
The aim of this study is to assess the effectiveness of biological markers in detecting fatigue/sleepiness in a sample of the general driving population in Belgium. The link between the collected biomarkers (oral fluid sample), observed signs of sleepiness in the driver and self-reported driver variables will be analysed. The analysis of the biological samples aims to measure endogenous metabolite levels that are possibly indicative for sleepiness of the donor driver. The respective metabolites will be chosen based on the results of a preceding clinical study (https://clinicaltrials.gov/study/NCT05585515). The objective of this study is to verify and validate the proposed metabolites as biomarkers for driver sleepiness in road traffic.
Researchers from NICC (National Institute of Criminalistics and Criminology) and VIAS will collect (1) saliva samples (Salivette with neutral swab allowing use by not-medically trained personnel; this sampling method is also used by the Belgian police in scope of the drugs in traffic legislation since 2019), (2) self-reported driver data (survey) and (3) observed driver data (form filled in by researchers) from drivers that were stopped on the road in scope of routine police checks. The collaboration with the police is because police can stop drivers randomly on-road while researchers cannot. After the police check, a researcher will ask if the driver wants to participate in a study on driver fatigue which is entirely independent from the police check. Voluntary drivers sign an informed consent form.
The collected saliva samples will be entirely separate from any sample obtained during the police checks. During data collection, the saliva sample, driver survey and observation form will each get a unique identification code to link the data. Afterwards, the researchers will work with this anonymised number and the data cannot be traced back to the participant.
All anonymised samples/data will temporarily be stored at NICC (Dept. Toxicology) and then be sent to the University of Zurich for analysis. The analysis of the saliva samples aims to measure endogenous metabolite levels that are possibly indicative for sleepiness of the donor. The correlation of the biomarker levels with observed/reported driver data will be measured. In specific cases the co-existence of drugs/medication in the saliva samples may also be tested: when the donor reported the consumption of the respective substance in the driver survey, as a confirmatory analysis, and (2) when the researchers believe the co-consumption of drugs/medication may interfere with the primary analysis. All anonymised samples will be stored at the University of Zurich for a maximum of 10 years and then be destroyed.
92 studies on the registry are indexed under Sleepiness; 20 are open to participants now.
This study's enrollment of 511 is above the median of 103 across 27 observational studies indexed under Sleepiness.
Browse Sleepiness studies →University of Zurich is the lead sponsor of 1,049 studies on the registry; 133 are open to participants now.
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Drivers (all vehicle types, aged 18 or older) voluntarily participating after being randomly stopped during roadside police checks in Belgium
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
People randomly stopped by police in public road traffic
Changes in metabolite concentrations in oral fluid quantified by liquid chromatography with mass spectrometry
Investigators will collect oral fluid samples for quantification of all detectable metabolites. Investigators will analyze which metabolite concentration values undergo significant changes with regard to sleep/wake history and demographical data of the donor.
Time frame: Baseline: One collection time point after enrollment
Subjective sleepiness
Participants will complete the Karolinska Sleepiness Scale (version A) questionnaire. It is a 9-point scale, ranging from 1 (extremely alert) to 9 (very sleepy, great effort to keep awake, fighting sleep).
Time frame: Baseline: One time point after enrollment
Behavioral markers of drowsy driving: Shivering
Investigators will examine participants for behavioral abnormalities concerning shivering based on this scale: (i) yes (ii) no (iii) uncertain
Time frame: Baseline: One time point after enrollment
Behavioral markers of drowsy driving: Reaction
Investigators will examine participants for behavioral abnormalities concerning reaction based on this scale: (i) slow/tired (ii) normal (iii) fast/talkative
Time frame: Baseline: One time point after enrollment
Behavioral markers of drowsy driving: Gait
Investigators will examine participants for behavioral abnormalities concerning gait based on this scale: (i) slow (ii) normal (iii) uncertain
Time frame: Baseline: One time point after enrollment
Plan to share: Undecided — Results will be published in peer-reviewed journals. Anonymized raw data will be made available upon request.
No publications or documents are linked to this record.
This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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