The effect of partial sleep deprivation on computer-based measures of fitness to drive

Road safety: The influence of vibration frequency on driver drowsiness, reaction time, and driving performance

Driver drowsiness is a factor in at least 20% of serious motor vehicle accidents. Although research has shown that Whole-Body Vibration (WBV) can induce drowsiness in drivers, it is unknown whether particular frequencies are more problematic. The present study systematically investigated the influence of WBV frequency on driver drowsiness. Fifteen participants each undertook six 1-h sessions of simulated driving while being subjected to WBV of either 0 Hz (no vibration), 1-4 Hz, 4-8 Hz, 8-16 Hz, 16-32 Hz or 32-64 Hz. Subjective sleepiness, as measured by the Karolinska Sleepiness Scale (KSS), confirmed that drivers felt drowsier when exposed to the two lowest frequency ranges (1-4 Hz and 4-8 Hz). Reaction time, which measures attention and alertness, was significantly impaired by the two lowest frequency ranges. Objective driving performance measures (Standard Deviation of Lane Position (SDLP), Standard Deviation of (SD) Steering Angle, Time in Unsafe Zone) also showed significant degradation due to exposure to the two lowest frequency ranges. Exposure to 1-4 Hz or 4-8 Hz vibration caused attention to become significantly impaired within 15-20 min and driving performance to be significantly impaired by 30-35 min. The other frequency ranges had little or no effect. These findings point to a need to develop equivalent vibration-induced drowsiness contours that can be adopted as transportation safety standards.

Prospective analyses of alertness, sleep, and fitness to drive one year after de novo multiple sclerosis diagnosis

BACKGROUND

The prevalence and functional burden of the chronic demyelinating disease multiple sclerosis (MS) are well documented; however, little is known about the initial clinical course of alertness, sleep, cognitive, and psychological symptoms.

OBJECTIVES

This exploratory, prospective, longitudinal study multidimensionally investigated the development and progression of alertness, sleep, fitness to drive, and psychological symptoms in the first year after de novo MS diagnosis.

METHODS

Twenty-five people with MS (pwMS) were assessed cognitively, psychologically, and using polysomnography soon after diagnosis and one year later, with outcomes compared to matched healthy controls.

RESULTS

In the early stage of the disease, psychological symptoms of pwMS were comparable with those of controls, and patient conditions did not deteriorate within the first disease year. A small percentage of pwMS experienced increased levels of anxiety and depression after diagnosis. Alertness, sustained attention, and fitness to drive were comparable between both groups, and fatigue levels remained low over the course of the year.

CONCLUSIONS

This study highlights patient experiences within the initial clinical course of MS in a small group of patients. Further research is needed to understand the progression of symptoms and impairments in MS over a longer period and in different stages of the disease.

The Effects of Napping on Wakefulness and Endurance Performance in Athletes: A Randomized Crossover Study

Background: Athletes often experience poor sleep quality due to stress, altitude exposure, travel across different time zones, and pre-competition nervousness. Coaches use daytime naps to counteract the negative effects of fragmented nighttime sleep. Napping before competitions has also been used to enhance performance in athletes without sleep problems, with mixed results in previous studies, particularly for endurance performance. Thus, we investigated the effects of napping after partial sleep deprivation (PSD) on endurance performance and wakefulness in athletes. Methods: We recruited 12 healthy and trained participants (seven female and five male) for a randomized crossover study design. The participants underwent two test sessions: a five-hour night of sleep without a nap (noNap) and a five-hour night of sleep with a 30-min nap opportunity (Nap30). Participants recorded their sleep-wake rhythm one week before and during the study using the Consensus Sleep Diary-Core and the Morningness-Eveningness Questionnaire to examine their circadian rhythm type. We quantified PSD and the nap with pupillography (pupil unrest index, PUI), a subjective level of sleepiness questionnaire (Karolinska Sleepiness Scale, KSS), and polysomnography. After each night, participants performed a maximal cycling ergometry test to determine time to exhaustion (TTE) and maximal oxygen uptake (VO _2max). Results: Participants had an average sleep duration of 7.2 ± 0.7 h and were identified as moderately morning types (n = 5), neither type (n = 5), and moderately evening types (n = 2). There was a significant difference in both sleepiness parameters between the two conditions, with the PUI (p = 0.015) and KSS (p ≤ 0.01) significantly decreased at 5 h and nap compared with only 5 h of sleep. The PUI (p ≤ 0.01) and KSS (p ≤ 0.01) decreased significantly from before to after the nap. However, there was no significant difference in physical exercise test results between the conditions for TTE (p = 0.367) or VO _2max (p = 0.308). Conclusions: Our results suggest that napping after light PSD does not significantly influence endurance performance. We conclude that aerobic performance is a multidimensional construct, and napping after PSD may not enhance it. However, napping is an effective method to increase wakefulness and vigilance, which can be beneficial for sports competitions.

Modeling road traffic fatalities in Iran's six most populous provinces, 2015-2016

BACKGROUND

Prevention of road traffic injuries (RTIs) as a critical public health issue requires coordinated efforts. We aimed to model influential factors related to traffic safety.

METHODS

In this cross-sectional study, the information from 384,614 observations recorded in Integrated Road Traffic Injury Registry System (IRTIRS) in a one-year period (March 2015-March 2016) was analyzed. All registered crashes from Tehran, Isfan, Fras, Razavi Khorasan, Khuzestan, and East Azerbaijan provinces, the six most populated provinces in Iran, were included in this study. The variables significantly associated with road traffic fatality in the uni-variate analysis were included in the multiple logistic regression.

RESULTS

According to the multiple logistic regression, thirty-two out of seventy-one different variables were identified to be significantly associated with road traffic fatality. The results showed that the crash scene significantly related factors were passenger presence(OR = 4.95, 95%CI = (4.54-5.40)), pedestrians presence(OR = 2.60, 95%CI = (1.75-3.86)), night-time crashes (OR = 1.64, 95%CI = (1.52-1.76)), rainy weather (OR = 1.32, 95%CI = (1.06-1.64)), no intersection control (OR = 1.40, 95%CI = (1.29-1.51)), double solid line(OR = 2.21, 95%CI = (1.31-3.74)), asphalt roads(OR = 1.95, 95%CI = (1.39-2.73)), nonresidential areas(OR = 2.15, 95%CI = (1.93-2.40)), vulnerable-user presence(OR = 1.70, 95%CI = (1.50-1.92)), human factor (OR = 1.13, 95%CI = (1.03-1.23)), multiple first causes (OR = 2.81, 95%CI = (2.04-3.87)), fatigue as prior cause(OR = 1.48, 95%CI = (1.27-1.72)), irregulation as direct cause(OR = 1.35, 95%CI = (1.20-1.51)), head-on collision(OR = 3.35, 95%CI = (2.85-3.93)), tourist destination(OR = 1.95, 95%CI = (1.69-2.24)), suburban areas(OR = 3.26, 95%CI = (2.65-4.01)), expressway(OR = 1.84, 95%CI = (1.59-2.13)), unpaved shoulders(OR = 1.84, 95%CI = (1.63-2.07)), unseparated roads (OR = 1.40, 95%CI = (1.26-1.56)), multiple road defects(OR = 2.00, 95%CI = (1.67-2.39)). In addition, the vehicle-connected factors were heavy vehicle (OR = 1.40, 95%CI = (1.26-1.56)), dark color (OR = 1.26, 95%CI = (1.17-1.35)), old vehicle(OR = 1.46, 95%CI = (1.27-1.67)), not personal-regional plaques(OR = 2.73, 95%CI = (2.42-3.08)), illegal maneuver(OR = 3.84, 95%CI = (2.72-5.43)). And, driver related factors were non-academic education (OR = 1.58, 95%CI = (1.33-1.88)), low income(OR = 2.48, 95%CI = (1.95-3.15)), old age (OR = 1.67, 95%CI = (1.44-1.94)), unlicensed driving(OR = 3.93, 95%CI = (2.51-6.15)), not-wearing seat belt (OR = 1.55, 95%CI = (1.44-1.67)), unconsciousness (OR = 1.67, 95%CI = (1.44-1.94)), driver misconduct(OR = 2.51, 95%CI = (2.29-2.76)).

CONCLUSION

This study reveals that driving behavior, infrastructure design, and geometric road factors must be considered to avoid fatal crashes. Our results found that the above-mentioned factors had higher odds of a deadly outcome than their counterparts. Generally, addressing risk factors and considering the odds ratios would be beneficial for policy makers and road safety stakeholders to provide support for compulsory interventions to reduce the severity of RTIs.

A systematic review of sleep deprivation and neurobehavioral function in young adults

AIM

To examine the effect of sleep deprivation (total and partial) on neurobehavioral function compared to a healthy sleep opportunity (7-9 h) in young adults 18-30 years.

BACKGROUND

More than one-third of young adults are sleep deprived, which negatively affects a range of neurobehavioral functions, including psychomotor vigilance performance (cognitive), affect, and daytime sleepiness.

METHODS

A systematic review of randomized controlled trials (RCTs) on sleep deprivation and neurobehavioral function. Multiple electronic databases (Cochrane Central Registry of Controlled Trials [CENTRAL], PubMed, PsycINFO, CINAHL, and Web of Science) were searched for relevant RCTs published in English from the establishment of each database to December 31, 2020.

RESULTS

Nineteen RCTs were selected (N = 766, mean age = 23.7 ± 3.1 years; 44.8% female). Seven were between-person (5 were parallel-group designs and 2 had multiple arms), and 12 were within-person designs (9 were cross over and 3 used a Latin square approach). Total sleep deprivation had the strongest detrimental effect on psychomotor vigilance performance, with the largest effects on vigilance tasks in young adults in the included studies.

CONCLUSION

Acute sleep deprivation degrades multiple dimensions of neurobehavioral function including psychomotor vigilance performance, affect, and daytime sleepiness in young adults. The effect of chronic sleep deprivation on the developing brain and associated neurobehavioral functions in young adults remains unclear.

Bus driver fatigue: A qualitative study of drivers in London

The research represents one of the first major qualitative studies to subjectively investigate fatigue amongst city bus drivers. Funded by TfL (grant no. 94050), the study considers the perspectives of both the bus drivers themselves and their managers. It explores opinion specifically in relation to how fatigue influences or is influenced by bus driving, and how this is managed. Data was collected from focus groups with bus drivers (n = 65 drivers) and one-to-one interviews with bus driver managers (n = 11). Fatigue was seen to be a problem, with all drivers having experienced for themselves the feeling of sleepiness whilst driving the bus, or knowing about it in others. The managers agreed that fatigue amongst drivers is evident, seeing it particularly as a contributor to serious incidents. Fatigue and sleepiness are not discussed between drivers as a general rule and they do not feel comfortable reporting instances of fatigue for fear of being disciplined. Managers would encourage drivers to report these issues and therefore hoped to create a more open culture. Factors identified as contributors to fatigue included: working overtime, having insufficient sleep, spending time with family, other non-work commitments, shift schedules, and work pressure.

Chronic sleep loss and risk-taking behavior: Does the origin of sleep loss matter?

Background: Many adolescents and young adults get insufficient sleep. A link between sleep loss and risk-taking behavior has been consistently found in the literature, but surprisingly, the role played by the origin of sleep loss in this link has never been investigated. Sleep loss can be voluntary (instead of sleeping, a significant amount of time is devoted to other activities) or involuntary (caused by a sleep disorder, for example, insomnia). The aim of this research was to investigate whether both types of sleep loss are associated to the same extent with risky behavior. Participants: Five hundred thirty-six university students between 19 and 25 years old participated in this study. Three groups were selected: participants with voluntary sleep loss, participants with insomnia, and normal sleepers. Methods: We assessed risk-taking behavior in virtual driving situations, as well as drinking habits in terms of quantity and frequency. To further explore the differences between the groups, we also measured sensation seeking, a personality trait related to risk-taking behavior. Results: Compared to participants with insomnia and normal sleepers, participants with voluntary sleep loss take more risks in dangerous driving situations, drink more alcohol, and have higher disinhibition scores on the Sensation-Seeking Scale. On the other hand, no such differences were found between participants with insomnia and normal sleepers, suggesting that sleep loss is not always associated with risk taking. Conclusions: Whether sleep loss is associated with risk-taking behavior or not could depend on the origin of sleep loss and the underlying personality traits.

The psychomotor vigilance task: Role in the diagnosis of hepatic encephalopathy and relationship with driving ability

BACKGROUND & AIMS

Hepatic encephalopathy (HE) is a syndrome of decreased vigilance and has been associated with impaired driving ability. The aim of this study was to evaluate the psychomotor vigilance task (PVT), which is used to assess both vigilance and driving ability, in a group of patients with cirrhosis and varying degrees of HE.

METHODS

A total of 145 patients (120 males, 59 ± 10 years, model for end-stage liver disease [MELD] score 13 ± 5) underwent the PVT; a subgroup of 117 completed a driving questionnaire and a subgroup of 106 underwent the psychometric hepatic encephalopathy score (PHES) and an electroencephalogram (EEG), based on which, plus a clinical evaluation, they were classed as being unimpaired (n = 51), or as having minimal (n = 35), or mild overt HE (n = 20). All patients were followed up for an average of 13 ± 5 months in relation to the occurrence of accidents and/or traffic offences, HE-related hospitalisations and death. Sixty-six healthy volunteers evenly distributed by sex, age and education served as a reference cohort for the PVT.

RESULTS

Patients showed worse PVT performance compared with healthy volunteers, and PVT indices significantly correlated with MELD, ammonia levels, PHES and the EEG results. Significant associations were observed between neuropsychiatric performance/PVT indices and licence/driving status. PVT, PHES and EEG results all predicted HE-related hospitalisations and/or death over the follow-up period; none predicted accidents or traffic offences. However, individuals with the slowest reaction times and most lapses on the PVT were often not driving despite having a licence. When patients who had stopped driving for HE-related reasons (n = 6) were modelled as having an accident or fine over the subsequent 6 and 12 months, PVT was a predictor of accidents and traffic offences, even after correction for MELD and age.

CONCLUSIONS

The PVT is worthy of further study for the purposes of both HE and driving ability assessment.

LAY SUMMARY

Hepatic encephalopathy (HE) is a complication of advanced liver disease that can manifest as excessive sleepiness. Some patients with HE have been shown to have difficulty driving. Herein, we used a test called the Psychomotor Vigilance Task (PVT), which measures sleepiness and can also be used to assess driving competence. We showed that PVT performance is fairly stable in healthy individuals. We also showed that PVT performance parallels performance in tests which are commonly used in cirrhotic patients to measure HE. We suggest that this test is helpful in quantifying HE and identifying dangerous drivers among patients with cirrhosis.

A systematic review of the effect of various interventions on reducing fatigue and sleepiness while driving

PURPOSE

To identify and appraise the published studies assessing interventions accounting for reducing fatigue and sleepiness while driving.

METHODS

This systematic review searched the following electronic databases: Medline, Science direct, Scopus, EMBASE, PsycINFO, Transport Database, Cochrane, BIOSIS, ISI Web of Knowledge, specialist road injuries journals and the Australian Transport and Road Index database. Additional searches included websites of relevant organizations, reference lists of included studies, and issues of major injury journals published within the past 15 years. Studies were included if they investigated interventions/exposures accounting for reducing fatigue and sleepiness as the outcome, measured any potential interventions for mitigation of sleepiness and were written in English. Meta-analysis was not attempted because of the heterogeneity of the included studies.

RESULTS

Of 63 studies identified, 18 met the inclusion criteria. Based on results of our review, many interventions in the world have been used to reduce drowsiness while driving such as behavioral (talking to passengers, face washing, listening to the radio, no alcohol use, limiting the driving behavior at the time of 12 p.m. - 6 a.m. etc), educational interventions and also changes in the environment (such as rumble strips, chevrons, variable message signs, etc). Meta-analysis on the effect of all these interventions was impossible due to the high heterogeneity in methodology, effect size and interventions reported in the assessed studies.

CONCLUSION

Results of present review showed various interventions in different parts of the world have been used to decrease drowsy driving. Although these interventions can be used in countries with high incidence of road traffic accidents, precise effect of each intervention is still unknown. Further studies are required for comparison of the efficiency of each intervention and localization of each intervention according to the traffic patterns of each country.

The neurocognitive consequences of sleep restriction: A meta-analytic review

The current meta-analytic review evaluated the effects of experimentally manipulated sleep restriction on neurocognitive functioning. Random-effects models were employed to estimate the overall effect size and the differential effect size across cognitive domains. Age, time of day, age-adjusted sleep deficit, cumulative days of restricted sleep, sleep latency, subjective sleepiness, and biological sex were examined as potential moderators of the effect. Based on a sample of 61 studies, from 71 different populations, findings revealed a significant negative effect of sleep restriction on cognitive processing across cognitive domains (g=-0.383, p<0.001). This effect held for executive functioning (g=-0.324, p<0.001), sustained attention (g=-0.409, p<0.001), and long-term memory (g=-0.192, p=0.002). There was insufficient evidence to detect an effect within the domains of attention, multitask, impulsive decision-making or intelligence. Age group, time of day, cumulative days of restricted sleep, sleep latency, subjective sleepiness, and biological sex were all significant moderators of the overall effect. In conclusion, the current meta-analysis is the first comprehensive review to provide evidence that short-term sleep restriction significantly impairs waking neurocognitive functioning.