Impaired driving performance associated with effect of time duration in patients with primary insomnia

Can inhaled cannabis users accurately evaluate impaired driving ability? A randomized controlled trial

Aims

To study the effect of inhaled cannabis on self-assessed predicted driving ability and its relation to reaction times and driving ability on a driving simulator.

Participants and methods

30 healthy male volunteers aged 18-34: 15 chronic (1-2 joints /day) and 15 occasional (1-2 joints/week) consumers. Self-assessed driving confidence (visual analog scale), vigilance (Karolinska), reaction time (mean reciprocal reaction time mRRT, psychomotor vigilance test), driving ability (standard deviation of lane position SDLP on a York driving simulator) and blood concentrations of delta-9-tétrahydrocannabinol (THC) were measured before and repeatedly after controlled inhalation of placebo, 10 mg or 30 mg of THC mixed with tobacco in a cigarette.

Results

Cannabis consumption (at 10 and 30 mg) led to a marked decrease in driving confidence over the first 2 h which remained below baseline at 8 h. Driving confidence was related to THC dose and to THC concentrations in the effective compartment with a low concentration of 0.11 ng/ml for the EC50 and a rapid onset of action (T1/2 37 min). Driving ability and reaction times were reduced by cannabis consumption. Driving confidence was shown to be related to driving ability and reaction times in both chronic and occasional consumers.

Conclusions

Cannabis consumption leads to a rapid reduction in driving confidence which is related to reduced ability on a driving simulator.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT02061020.

Driving Behaviour in Depression Based on Subjective Evaluation and Data from a Driving Simulator

Road traffic collisions are a major issue for public health. Depression is characterized by mental, emotional and executive dysfunction, which may have an impact on driving behaviour. Patients with depression (N = 39) and healthy controls (N = 30) were asked to complete questionnaires and to drive on a driving simulator in different scenarios. Driving simulator data included speed, safety distance from the preceding vehicle and lateral position. Demographic and medical information, insomnia (Athens Insomnia Scale, AIS), sleepiness (Epworth Sleepiness Scale, ESS), fatigue (Fatigue Severity Scale, FSS), symptoms of sleep apnoea (StopBang Questionnaire) and driving (Driver Stress Inventory, DSI and Driver Behaviour Questionnaire, DBQ) were assessed. Gender and age influenced almost all variables. The group of patients with depression did not differ from controls regarding driving behaviour as assessed through questionnaires; on the driving simulator, patients kept a longer safety distance. Subjective fatigue was positively associated with aggression, dislike of driving, hazard monitoring and violations as assessed by questionnaires. ESS and AIS scores were positively associated with keeping a longer safety distance and with Lateral Position Standard Deviation (LPSD), denoting lower ability to keep a stable position. It seems that, although certain symptoms of depression (insomnia, fatigue and somnolence) may affect driving performance, patients drive more carefully eliminating, thus, their impact.

Distracted driving behavior in patients with insomnia

Insomnia is one of the most common sleep disorders and is characterized by a subjective perception of difficulty falling asleep. Drivers with insomnia are vulnerable to distraction and exhibit higher levels of risk while driving. This study investigated the effect of two sources of in-vehicle distractions on the driving performance of drivers with insomnia and good sleepers by analyzing different driving behavior measures. Twenty-one drivers with insomnia and twenty-one healthy volunteers were recruited to complete simulated driving dual tasks. The primary task required the participants to perform: (a) a lane-keeping task, and (b) a lane-change task. The secondary task required the participants to deal with: (a) baseline (non-task), (b) internal distraction task, and (c) external distraction task. The internal distraction task required participants to complete quantitative reasoning tasks, while the external distraction task was a 0-back test. The relationship between distracted driving ability and cognitive function was also investigated. The results demonstrate that for lane-keeping tasks, drivers with insomnia had significantly higher standard deviations (SD) for speed, throttle position, acceleration, and lateral position than healthy drivers under internal distraction, but the driving performance did not differ significantly between groups under internal distraction or baseline. In the lane-change task, drivers with insomnia had higher SDs for steering wheel angle, steer angular velocity, lateral acceleration, and lateral speed than healthy drivers under external distraction. Moreover, external distraction impaired driving behavior in the healthy group, while internal distraction impaired driving ability in both groups. Healthy drivers with cognitive impairment displayed impaired lane-keeping abilities under internal distractions and impaired lane-changing abilities under external distractions. Driving performance in the insomnia group was not significantly associated with cognitive function. The results demonstrate that insomnia and distraction impair driving ability, and driver performance is affected differently by the distraction source (internal or external). The driving ability of healthy drivers with decreased cognition was impaired, but not that of insomniacs.The findings of this study provide new insights for preventing and estimating the potential influence of distracted driving behavior in individuals with insomnia.

Hypnotic Medications as an Adjunct Treatment to Cognitive Behavioral Therapy for Insomnia

Cognitive behavioral therapy for insomnia (CBT-I) is the universally recommended treatment of choice for insomnia disorder based on its safety and posttreatment durability of benefit. However, CBT-I does not help all patients achieve remission. The second most evidence-based treatment, hypnotic pharmacotherapy (PCT), does not resolve perpetuating factors of insomnia, resulting in potential waning of benefit and dependence. This article presents a rationale that supports consideration of hypnotic augmentation of CBT-I (COMB), along with a review of select randomized controlled trials relevant to clinical decision-making.

Armodafinil to reduce the sleepiness related side-effects of sleep restriction therapy being used to treat insomnia disorder: An open label clinical trial pilot study compared with historical controls

Sleep restriction therapy (SRT) is an effective stand-alone behavioural intervention for insomnia disorder. However, its daytime side effects, particularly sleepiness, may be troubling for patients and/or may be a necessary part of the patient's treatment journey. This pilot trial aims to explore the potential benefit of armodafinil, a wakefulness promoter. Patients were treated with SRT with open label adjunctive armodafinil (150 mg/day). Thirty-three patients from previous studies that have undergone exactly the same SRT intervention acted as controls. The primary outcome measure was the insomnia severity index (ISI), and secondary outcomes were the Epworth sleepiness scale, sleep restriction adherence scale (SRAS), and safety from baseline through to 12 weeks. We recruited 25 patients into the trial. Data for the primary end point (ISI at 12 weeks) was available for 20 of the participants. The baseline insomnia severity index was 20.2 (SD 3.3) and decreased to 9.1 (SE 1.1), with no change, to 10.2 and 11.2 at weeks 6 and 12 respectively (all p > 0.05 compared with baseline). The insomnia severity index values for armodafinil patients were statistically inferior to historical controls at the primary time point of 12 weeks (11.2 vs. 6.7, p < 0.01). Sleep restriction therapy plus armodafinil treatment was associated with frequent minor side effects but was generally safe and acceptable to patients. Sleep restriction therapy was associated with a robust clinical response in the insomnia severity index values for insomnia patients. Based upon historical control data, armodafinil does not appear to have beneficial adjunctive effects in addition to sleep restriction therapy alone.

Fatigue performance in patients with chronic insomnia

Insomnia is associated with fatigue and poor driving performance, thus increasing the risk of traffic accidents. This study aimed to evaluate the effect of fatigue on driving in patients with chronic insomnia in a free-flow traffic scenario and car-following scenario, and to investigate the relationships between driving performance, cognitive function, and insomnia. The Trail Making Test (TMT), Stroop Color and Word Test (SCWT), Symbol Digit Modalities Test (SDMT), and Digit Span Test (DST) of 15 participants with mild-to-moderate chronic insomnia and 16 healthy participants were assessed. During the fatigue driving task, drivers completed simulated driving tasks under free-flow traffic and car-following scenarios. The mean speed (MS), mean acceleration (MA), mean lateral position (MLP), and standard deviation of lateral position (SDLP) were measured to assess driving performance. During fatigued tasks, the MA and MLP in the free-driving scenario were higher than those in the car-following scenario (P < 0.01), the SDLP was higher in the insomnia group than in the healthy group (P = 0.02), and the interaction effect was significantly different for MLP between the groups (P = 0.03). MS was negatively correlated with TMT score, SDMT score, and DST score, and positively correlated with time to complete TMT, errors in SCWT, and time to complete SCWT. SDLP was negatively correlated with DST score and positively correlated with time to complete SCWT. Furthermore, the insomnia group had poorer lateral vehicle control ability than the healthy group. The insomnia group had a more impaired driving performance in the free-driving scenario than in the car-following scenario. Drivers with impaired cognitive function exhibited impaired driving performance.

Measuring the effects of mind wandering in people with insomnia: A driving simulator study

Purpose

Studies have shown that individuals with insomnia experience more frequent and longer episodes of mind wandering (MW) while driving. However, the effect of the interaction between insomnia and MW on driving behavior is not fully understood. This study aimed to gain deeper insights into the relationships among insomnia, MW, and driving behavior.

Patients and methods

Forty-two participants (21 diagnosed with insomnia and 21 controls) were recruited, and subjective sleep quality and cognitive function were assessed. A driving simulator experiment with a within-subject design was performed, involving two distraction tasks (no-distraction task versus MW task) and two driving scenarios (lane-keeping versus lane-changing).

Results

In the lane-keeping scenario, there was no significant between-group difference (people with insomnia and controls) in longitudinal driving performance for the no-distraction task, although the interaction between MW and insomnia significantly increased drivers’ longitudinal control variation. Correlation analysis confirmed that longitudinal driving performance was positively correlated with sleep quality and the cognitive level. Unlike longitudinal driving performance, lateral driving performance was significantly weaker in people with insomnia than in controls under both distraction tasks. In the lane-changing scenario, although there was no between-group difference in driving performance, the MW task led to significant changes in driving performance within each group compared with the no-distraction task, and these findings were associated with cognitive function, but not with sleep quality.

Conclusion

These findings show that insomnia and MW combined can lead to reduced driving performance. Further research is needed to elucidate the factors that influence this phenomenon.

Fidelity of Information Processing on a Psychomotor Vigilance Task Predicts Changes in Self-Reported Sleepiness Ratings

INTRODUCTION

Daytime sleepiness is a common problem. Although sleepiness is primarily assessed at the self-report unit of analysis, factors that contribute to an individual's experience and report of sleepiness remain poorly understood. While sleepiness is known to impact vigilance performance, the impact of vigilance performance on sleepiness reports is less well understood. We aimed to explore how performance on a psychomotor vigilance task (PVT) relates to changes in self-reported sleepiness in a rested condition.

METHODS

Participants were 66 adults (Mdn=23, range 18-49 years old), 47% female, 88% white, with a wide range of insomnia symptoms. Participants rated their sleepiness on a scale from 1 (not sleepy) to 10 (extremely sleepy) at the start (pre) and the end (post) of a 10-minute computerized PVT. Ordinal regression determined whether mean reciprocal reaction time, a measure of overall performance, or the log-transformed signal-to-noise ratio (LSNR), a measure of fidelity of information processing, predicted post-sleepiness, adjusting for pre-sleepiness, insomnia, and potential confounds.

RESULTS

Lower LSNR predicted greater change in sleepiness (pre-to-post PVT) and higher post-sleepiness even after adjusting for pre-sleepiness, mean reciprocal reaction time, insomnia, and other potential confounds (p<0.05).

DISCUSSION

When adjusting for insomnia symptoms and potential confounds, participants with lower fidelity of information processing reported higher sleepiness than they had reported at the start of the PVT. Possible mechanisms and explanations are discussed in relation to a 3-factor model of sleep-wake states. This line of research may contribute to innovative approaches to assessing and treating sleepiness.

Do hypnotics increase the risk of driving accidents or near miss accidents due to hypovigilance? The effects of sex, chronic sleepiness, sleep habits and sleep pathology

Driving accidents due to hypovigilance are common but the role of hypnotics is unclear in patients suffering from sleep disorders. Our study examined factors influencing accidents and near miss accidents attributed to sleepiness at the wheel (ANMAS). Using data from an online questionnaire aimed at patients with sleep disorders, we analysed the associations between ANMAS, sociodemographic data, symptoms of sleep disorders, severity of insomnia (Insomnia Severity Index (ISI)) symptoms of anxiety and depression (Hospital Anxiety and Depression scale with depression (HADD) and anxiety (HADA) subscales), chronic sleepiness (Epworth sleepiness scale ESS), hypnotic use and information about sleep habits. Hypnotics were hierarchically grouped into Z-drugs, sedative medication, melatonin and over the counter (OTC) alternative treatments. Of 10802 participants; 9.1% reported ANMAS (Men 11.1% women 8.3%) and 24.4% took hypnotics (Z-drugs 8.5%, sedative medication 8%, melatonin 5.6% and alternative treatments 2.5%). Logistic regression analysis identified the following risk factors for ANMAS: moderate (OR 2.4; CI: 2.10-2.79) and severe sleepiness (ESS OR 5.66; CI: 4.74-6.77), depression (HADD OR 1.2; CI: 1.03-1.47), anxiety (HADA OR 1.2;CI: 1.01-1.47), and insufficient sleep (OR1.4; CI: 1.2-1.7). Hypnotics were not associated with an increased risk of ANMAS in patients suffering from insomnia. Risk factors varied according to sex: in females, sex (OR 0.; CI: 0.55-0.74), mild insomnia (OR 0.5; CI: 0.3-0.8) and use of alternative treatments (OR 0.455, CI:0.23-0.89) were protective factors and risk was increased by sleepiness, sleep debt, social jetlag, caffeine use, anxiety and depression. In men no protective factors were identified: sleepiness, sleep debt, and severe insomnia were associated with an increased risk of ANMAS. In clinical practice, all patients with daytime sleepiness and men with severe insomnia should be counselled concerning driving risk and encouraged to avoid sleep debt.

Cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC) for chronic insomnia disorder ('CANSLEEP' trial): protocol for a randomised, placebo-controlled, double-blinded, proof-of-concept trial

INTRODUCTION

Insomnia is a highly prevalent and costly condition that is associated with increased health risks and healthcare utilisation. Anecdotally, cannabis use is frequently reported by consumers to promote sleep. However, there is limited research on the effects of cannabis on sleep and daytime function in people with insomnia disorder using objective measures. This proof-of-concept study will evaluate the effects of a single dose of an oral cannabis-based medicine on sleep and daytime function in participants with chronic insomnia disorder.

METHODS AND ANALYSIS

A randomised, crossover, placebo-controlled, single-dose study design will be used to test the safety and efficacy of an oral oil solution ('ETC120') containing 10 mg Δ9-tetrahydrocannabinol (THC) and 200 mg cannabidiol (CBD) in 20 participants diagnosed with chronic insomnia disorder. Participants aged 35-60 years will be recruited over an 18-month period commencing August 2019. Each participant will receive both the active drug and matched placebo, in a counterbalanced order, during two overnight study assessment visits, with at least a 1-week washout period between each visit. The primary outcomes are total sleep time and wake after sleep onset assessed via polysomnography. In addition, 256-channel high-density electroencephalography and source modelling using structural brain MRI will be used to comprehensively examine brain activation during sleep and wake periods on ETC120 versus placebo. Next-day cognitive function, alertness and simulated driving performance will also be investigated.

ETHICS AND DISSEMINATION

Ethics approval was received from Bellberry Human Research Ethics Committee (2018-04-284). The findings will be disseminated in a peer-reviewed open-access journal and at academic conferences.

TRIAL REGISTRATION NUMBER

ANZCTRN12619000714189.

Tired and lack focus? Insomnia increases distractibility

Chronic insomnia is associated with subjective daytime cognitive dysfunction, but objective corroborative data are often lacking. In this study, we use Perceptual Load Theory to objectively assess distractibility in participants with insomnia ( N = 23) compared with age- and sex-matched controls ( N = 23). Following overnight supervised sleep observation, all participants completed a selective attention task which varied in the level of perceptual load and distractor congruency. The insomnia group was found to be more distracted than controls, whereas their selective attention mechanism appeared to be intact, with reduced distractor processing under high load for both groups. Insomnia symptom severity was positively correlated with participant distractibility. These findings suggest that there are insomnia-related daytime cognitive impairments that are likely to arise from compromised cognitive control rather than an ineffective selective attention mechanism. This task may be clinically useful in assessing daytime impairments, and potentially treatment response, in those with insomnia.

Primary insomnia patients' performances during simulated car following and urban driving in the afternoon

According to epidemiological studies, insomnia is associated with an increase in risk of traffic accidents. Recent investigations revealed that patients with insomnia had driving performance impairment under monotonous conditions. However, it is unclear whether other driving abilities may be impacted by insomnia, especially those needing more attentional resources than those involved in monotonous driving. Other findings revealed that impaired performances are more likely to occur with the increase of cognitive demands. However, such tests did not reflect difficulties in situations of everyday life expressed by patients with insomnia, such as driving in an urban environment with traffic and critical situations. Therefore, behaviour in situations encountered in everyday life has to be explored. The aim of the present study was to assess driving performances of patients with insomnia in daily routine tasks such as urban and car-following tests. For this purpose, 15 patients with insomnia and 16 good sleepers performed an urban test of driving with original risk scenarios and a car-following test during the middle afternoon. No significant behavioural difference between patients with insomnia and good sleepers has been found in both the urban test and the car-following test, showing that patients with insomnia have no impairment in behaviour implicated in daily contexts driving tasks of short period of time performed in the late afternoon. Although our results provide a first step towards knowledge of behavioural performance during daily routine driving tasks in patients with insomnia, future studies are needed using on-the-road driving tests and/or different population of patients with insomnia before generalisation.

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.

High risk of obstructive sleep apnea, insomnia, and daytime sleepiness among commercial motor vehicle drivers

PURPOSE

We investigated the prevalence of sleep problems, such as obstructive sleep apnea (OSA), insomnia, and daytime sleepiness in commercial motor vehicle (CMV) drivers compared with that in the general population.

METHODS

This is a cross-sectional study comparing sleep habits and sleep problems in 110 truck drivers with 1001 matched controls from the general population. The assessment was based on self-administered questionnaires that included the Berlin questionnaire, the insomnia severity index, and the Epworth sleepiness scale (ESS). Multivariate regression analysis was performed to determine whether CMV drivers were independently associated with these sleep problems compared with controls.

RESULTS

The prevalence of a high risk of OSA and insomnia was 35.5% and 15.2%, respectively, in CMV drivers, which was significantly higher than in controls with a prevalence of 12.2% and 4.1%, respectively (P < 0.001 for both). Although CMV drivers showed higher ESS scores than controls, the prevalence of daytime sleepiness did not differ between the two groups (19.1% vs. 16.8%, P = 0.54). After adjusting for covariates, CMV drivers had 3.68 times higher odds (95% CI 2.29-5.84) of OSA and 2.97 times higher odds (95% CI, 1.46-6.06) of insomnia compared with controls. However, the degree of daytime sleepiness was not independently associated with CMV drivers.

CONCLUSIONS

The prevalence of OSA and insomnia in CMV drivers was higher than that in the general population. Daytime sleepiness was associated with increased BMI, depression, OSA, and short sleep duration, regardless of CMV driving as an occupational factor.

Evidence of attentional impairments using virtual driving simulation in multiple sclerosis

BACKGROUND

Detection of attentional disorders in complex situation related to daily life activities in multiple sclerosis patients needs better adapted tools than traditional cognitive assessment.

OBJECTIVE

To investigate the usefulness of virtual reality assessment of attention in multiple sclerosis, especially to evaluate alertness and divided attention using driving simulation.

METHODS

In this preliminary study, 11 relapsing-remitting patients (median EDSS: 2; mean disease duration of 10.3 years) and 11 healthy matched controls performed a driving simulation under three conditions (monotonous driving, divided attention driving and urban driving) where Standard Deviation of Lateral position (SDLP) was the main evaluated criteria. In comparison, traditional cognitive assessment of attentional functions was administered (SDMT, alertness and divided attention of TAP battery). Statistical non-parametric Mann-Whitney U tests were used to compare performances between groups in the two types of assessments. Exploratory correlational analyses were further conducted.

RESULTS

No significant difference was observed between groups for traditional attentional assessment except for information processing speed (SDMT; p < 0.01). Considering virtual reality, patients were less efficient than controls on the primary parameter of safe driving (SDLP; p < 0.05). They also committed more errors and omissions (p < 0.01) and speed fluctuations (p < 0.01) during the divided-attention driving condition. Urban driving did not reveal difference between groups. Lack of significant correlations between traditional and virtual reality attentional assessment suggested that they do not evaluate the same cognitive processes.

CONCLUSION

Patients experienced difficulties in maintaining the trajectory and the speed of the simulated vehicle which may be indicative of attentional difficulties, especially alertness and divided attention. These impairments were not revealed by the traditional cognitive assessment. Results of this preliminary study shed new light about the usefulness of virtual reality techniques and their future interest as a part of cognitive rehabilitation programs. They also highlights the need to develop driving preventive measures in MS.

Insomnia is associated with road accidents. Further evidence from a study on truck drivers

BACKGROUND

Sleep-related problems are known risk factors for road accidents. However, very few studies have investigated the role played by insomnia and its components, and no data are available for a population of occupational drivers at risk, such as the truck driver category.

OBJECTIVE

To measure the prevalence and impact of insomnia on motor vehicle accidents (MVAs) and near-miss accidents (NMAs) in 949 truck drivers.

DESIGN

Cross-sectional survey.

RESULTS

Insomnia affected 27.5% of the sample. Compared to other drivers, in the 3 years prior to the study, truck drivers with insomnia had reported a significantly higher number of MVAs; they had also reported a greater number of NMAs in the previous 6 months. After correction for the presence of obstructive sleep apnea, excessive daytime sleepiness, short sleep duration, and other concurrent diseases, insomniac truck drivers had an almost two-fold risk of driving accidents (OR: 1.82, CI 95%:1.33-2.49) and a more than three-fold increased risk of near-miss accidents (OR: 3.35, CI95%:2.06-5.45) compared to non-insomniac drivers.

CONCLUSION

Insomnia emerged as an independent risk factor for MVAs and NMAs. We strongly advise screening commercial drivers for signs and symptoms of insomnia in order to improve health and safety on the road.

New, Occasional, and Frequent Use of Zolpidem or Zopiclone (Alone and in Combination) and the Risk of Injurious Road Traffic Crashes in Older Adult Drivers: A Population-Based Case-Control and Case-Crossover Study

BACKGROUND

Previous studies on the effect of zolpidem or zopiclone use on the risk of road traffic crashes (RTCs) have shown mixed results.

OBJECTIVE

Our objective was to determine the association between zolpidem or zopiclone use (as separate drugs or combined) and the occurrence of injurious RTCs among older adult drivers.

METHODS

This was a population-based matched case-control and case-crossover study based on secondary data linked together from Swedish national registers. Cases were drivers aged 50-80 years involved in a vehicle crash resulting in injuries between January 2006 and December 2009 for the case-control study (n = 27,096) and from February 2006 to December 2009 for the case-crossover study (n = 26,586). For the first design, four controls were matched to each case by sex, age, and residential area, and exposure was categorized into new, occasional, and frequent use of zolpidem only, zopiclone only, and combined zolpidem and zopiclone. For the case-crossover study, newly dispensed zolpidem or zopiclone users were assessed during the 28 days prior to the crash and compared with an equally long control period using a 12-week washout period. Matched adjusted odds ratios (OR) were computed using conditional logistic regression.

RESULTS

Increased ORs for all users were observed. In the case-control study, the highest odds were seen among newly initiated zolpidem-only users involved in single-vehicle crashes (adjusted OR 2.27; 95% confidence interval [CI] 1.21-4.24), followed by frequent combined zolpidem and zopiclone users [adjusted OR 2.20; CI 1.21-4.00]. In the case-crossover, newly initiated treatment with zolpidem or zopiclone showed an increased risk that was highest in the 2 weeks after the start of the treatment (OR 2.66; 95% CI 1.04-6.81).

CONCLUSIONS

These results provide more compelling evidence for the role of zolpidem or zopiclone in the occurrence of RTCs among older adults, not only in frequent users, but also at the beginning of treatment.

Circadian Characteristics of Older Adults and Aerobic Capacity

BACKGROUND

Alteration of circadian rhythmicity with aging might depend on physical aerobic capacity.

METHODS

Three groups of participants were established based on their peak oxygen consumption (Group 1 < 20mL/min/kg; Group 2 > 20mL/min/kg and <30mL/min/kg; Group 3 > 30mL/min/kg). Each participant had an individual evaluation of their circadian rhythmicity characteristics through two well-known circadian rhythms: core temperature and rest/activity cycles. Nocturnal sleep was also recorded using actimetry and diurnal vigilance tested in a car driving simulator.

RESULTS

The amplitude of the oral temperature fluctuations for Group 1 is significantly lower (p < .05) than that of Group 3. Group 2 (p < .01) and Group 3 (p < .05) were significantly more active during the day than Group 1. The index of inactivity during the night for Groups 2 (p < .05) and 3 (p < .01) was higher than Group 1. Results of the car driving simulation showed that for Group 1, the number of lane crossings was significantly higher than Groups 2 (p < .01) and 3 (p < .01). In addition, diurnal vigilance was lower in Group 1.

CONCLUSIONS

The biological clock seems to be enhanced in older participants with a higher level of physical capacity.

Specific EEG sleep pattern in the prefrontal cortex in primary insomnia

OBJECTIVE

To assess the specific prefrontal activity in comparison to those in the other main cortical areas in primary insomnia patients and in good sleepers.

METHODS

Fourteen primary insomnia patients and 11 good sleepers were included in the analysis. Participants completed one night of polysomnography in the sleep lab. Power spectra were calculated during the NREM (Non-rapid eyes movements) and the REM (Rapid eyes movements) sleep periods at prefrontal, occipital, temporal and central electrode positions.

RESULTS

During the NREM sleep, the power spectra did not differ between groups in the prefrontal cortex; while primary insomnia patients exhibited a higher beta power spectrum and a lower delta power spectrum compared to good sleepers in other areas. During the REM sleep, the beta1 power spectrum was lower in the prefrontal cortex in primary insomnia patients compared to good sleepers; while no significant difference between groups was obtained for the other areas.

CONCLUSIONS

The present study shows a specific prefrontal sleep pattern during the whole sleep period. In addition, we suggest that primary insomnia patients displayed a dysfunction in the reactivation of the limbic system during the REM sleep and we give additional arguments in favor of a sleep-protection mechanism displayed by primary insomnia patients.