Hélène Dirix

Dr. Hélène Dirix

orcid

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 March 2024 in JMIR mHealth and uHealth
Verified
Journal Article
Open access
ASAn-Marie Schyvens
An-Marie Schyvens
COCatharina Nina Van Oost
Catharina Nina Van Oost
Jean-Marie AertsJean-Marie Aerts
Jean-Marie Aerts
FMFederica Masci
Federica Masci
BPBrent PETERS
Brent PETERS
JVJohan Verbraecken
Johan Verbraecken
Background: Despite being the gold-standard method for objectively assessing sleep, polysomnography (PSG) faces several limitations as it is expensive, time-consuming, and labor-intensive; requires various equipment and technical expertise; and is impractical for long-term or in-home use. Consumer wrist-worn wearables are able to monitor sleep parameters and thus could be used as an alternative for PSG. Consequently, wearables gained immense popularity over the past few years, but their accuracy has been a major concern. Objective: A systematic review of the literature was conducted to appraise the performance of 3 recent-generation wearable devices (Fitbit Charge 4, Garmin Vivosmart 4, and WHOOP) in determining sleep parameters and sleep stages. Methods: Per the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement, a comprehensive search was conducted using the PubMed, Web of Science, Google Scholar, Scopus, and Embase databases. Eligible publications were those that (1) involved the validity of sleep data of any marketed model of the candidate wearables and (2) used PSG or an ambulatory electroencephalogram monitor as a reference sleep monitoring device. Exclusion criteria were as follows: (1) incorporated a sleep diary or survey method as a reference, (2) review paper, (3) children as participants, and (4) duplicate publication of the same data and findings. Results: The search yielded 504 candidate articles. After eliminating duplicates and applying the eligibility criteria, 8 articles were included. WHOOP showed the least disagreement relative to PSG and Sleep Profiler for total sleep time (−1.4 min), light sleep (−9.6 min), and deep sleep (−9.3 min) but showed the largest disagreement for rapid eye movement (REM) sleep (21.0 min). Fitbit Charge 4 and Garmin Vivosmart 4 both showed moderate accuracy in assessing sleep stages and total sleep time compared to PSG. Fitbit Charge 4 showed the least disagreement for REM sleep (4.0 min) relative to PSG. Additionally, Fitbit Charge 4 showed higher sensitivities to deep sleep (75%) and REM sleep (86.5%) compared to Garmin Vivosmart 4 and WHOOP. Conclusions: The findings of this systematic literature review indicate that the devices with higher relative agreement and sensitivities to multistate sleep (ie, Fitbit Charge 4 and WHOOP) seem appropriate for deriving suitable estimates of sleep parameters. However, analyses regarding the multistate categorization of sleep indicate that all devices can benefit from further improvement in the assessment of specific sleep stages. Although providers are continuously developing new versions and variants of wearables, the scientific research on these wearables remains considerably limited. This scarcity in literature not only reduces our ability to draw definitive conclusions but also highlights the need for more targeted research in this domain. Additionally, future research endeavors should strive for standardized protocols including larger sample sizes to enhance the comparability and power of the results across studies.

1 June 2021 in Journal of Safety Research
Verified
Journal Article
Closed access
EMEva Michelaraki
Eva Michelaraki
Christos KatrakazasChristos Katrakazas
Christos Katrakazas
George YannisGeorge Yannis
George Yannis
AFAshleigh Filtness
Ashleigh Filtness
RTRachel Talbot
Rachel Talbot
RTRodrigo Taveira
Rodrigo Taveira

6 November 2022 in Autism
Verified
Journal Article
Closed access
HDHélène Dirix
Hélène Dirix
VRVeerle Ross
Veerle Ross
KBKris Brijs
Kris Brijs
LBLaura Bertels
Laura Bertels
WAWael Alhajyaseen
Wael Alhajyaseen
ASAnnemie Spooren
Annemie Spooren
Community participation and the formation of social networks are crucial for a qualitative life. To this end, transportation plays an essential role. Many autistic people rely on public transportation for their mobility needs. However, research shows that it is not always easy for them to use it. The issues they face when using public bus transport have not yet been thoroughly studied. The current case study in Flanders aimed to give autistic people the opportunity to express the issues they face while using public bus transportation. A qualitative hermeneutic phenomenological study was carried out. Semistructured interviews were conducted with 17 autistic individuals. The interviews were analyzed based on the interpretative phenomenological analysis method. Three main themes emerged: creating predictability, limiting stimuli, and open and accessible communication. In addition, various coping strategies were described, such as the use of noise-canceling headphones. The results of this study may lead to a more autism-friendly public transportation environment. Lay Transportation plays an essential role in daily life, allowing people to participate in the community and form social relationships. Many autistic people rely on public transportation to meet their mobility needs. However, research shows that it is not always easy for them to use it. The exact issues autistic individuals face when traveling with public transportation and how public transportation can be made more autism-friendly have yet to be researched. The current study allowed autistic individuals to express themselves regarding issues they face while traveling by public bus transportation, to raise awareness for making public transportation more autism-friendly. We interviewed 17 autistic individuals about their experiences riding the bus. Three main themes emerged from the results: creating predictability, limiting stimuli, and open and accessible communication. If transport companies take initiatives related to these themes, autistic people traveling by bus can have a more pleasant experience. Participants also described coping strategies for stressful or uncomfortable situations while using public bus transportation, such as using noise-cancelling headphones or digital applications for real-time route tracking, etc. These findings may lead to a more autism-friendly public transportation.

13 October 2025 in Sensors
Verified
Journal Article
Open access
PDF file
COCatharina Nina Van Oost
Catharina Nina Van Oost
FMFederica Masci
Federica Masci
AMAdelien Malisse
Adelien Malisse
ASAn-Marie Schyvens
An-Marie Schyvens
BPBrent PETERS
Brent PETERS
Jean-Marie AertsJean-Marie Aerts
Jean-Marie Aerts
Wearable devices are increasingly used for health and stress monitoring, yet their accuracy under dynamic, real-world conditions remains uncertain. This study validated the heart rate measurement accuracy of one chest-worn device (Zephyr BioHarness 3.0), a research-grade wrist-worn device (EmbracePlus), and five commercial wrist-worn wearable devices (Fitbit Charge 5, Fitbit Sense 2, Garmin Vivosmart 4, WHOOP 4.0, and Withings Scanwatch) against a 12-lead ECG using a 20 min protocol simulating real-life dynamics, including rest and varied-intensity walking. Device performance was evaluated across the full protocol and during transient states, defined as periods of rapid heart rate change. Accuracy and agreement were evaluated across per-second, 10 s, and 60 s resolutions. The Zephyr device showed a strong performance during all dynamic conditions. Among the wrist-worn devices, the Fitbit Charge 5 and Sense 2 showed the highest accuracy overall, while the Garmin Vivosmart 4 demonstrated greater stability during transitions. The WHOOP 4.0, Withings Scanwatch, and EmbracePlus devices performed acceptably during steady-state conditions, but were less accurate during transitions. Performance notably declined across all wrist-worn devices during transient states, with motion onset and large step changes in heart rate exacerbating measurement errors. Larger averaging windows improved accuracy by smoothing variability. The findings underscore that wrist-worn wearable devices may be better suited for average and trend heart rate monitoring rather than capturing acute dynamics. However, the Garmin and Fitbit devices showed suitable when requiring moderate accuracy during dynamic conditions. These results highlight the importance of context-specific validation and informed device selection to ensure effective use in health and stress-related applications.

15 March 2023 in Sustainability
Verified
Journal Article
Open access
PDF file
BVBart De Vos
Bart De Vos
ACAriane Cuenen
Ariane Cuenen
VRVeerle Ross
Veerle Ross
HDHélène Dirix
Hélène Dirix
KBKris BRIJS
Kris BRIJS
Tom BrijsTom Brijs
Tom Brijs
Speeding is one of the leading risk factors in road safety. Not only is it one of the leading causes of accidents, but it also has an extensive effect on the impact and consequences of accidents. This is especially the case for trucks, where the enforced speed limit is often dependent on local legislation and context rather than speed limit traffic signs. This study is part of the greater i-DREAMS project and aims to explore the effectiveness of an intelligent speed assistance system for truck drivers on different road types. To achieve this, a simulator experiment was performed with 34 professional truck drivers in Belgium. Participants first made a baseline drive, followed by two more drives, where they received visual information about the enforced speed limit but also visual and auditory warnings when exceeding the speed limit. The drives included different road environments with different speed limits. The results reveal a significant reduction in relevant parameters (i.e., average speed, minimum speed, maximum speed, and percentage of distance above the speed limit) when drivers received information and warnings about speeding while driving on a rural 1 × 1 road with a speed limit of 70 km/h (60 km/h for trucks). Further research is needed to validate this effect on other road types and under more-challenging conditions.

3 May 2024 in Case Studies on Transport Policy
Verified
Journal Article
Open access
WMWondwesen Girma Mamo
Wondwesen Girma Mamo
Wael AlhajyaseenWael Alhajyaseen
Wael Alhajyaseen
HDHélène Dirix
Hélène Dirix
KBKris BRIJS
Kris BRIJS
Tom BrijsTom Brijs
Tom Brijs
VRVeerle Ross
Veerle Ross