Abstract |
Background: Drowsiness and sleeping at the wheel have been identified as important
causes behind driving impairment and severe road crashes related to sleepiness. Sleep
deprivation and undetected sleep disorders such as insomnia, narcolepsy and sleep
apnea may possibly result to drowsy driving and increase the risk of accident
involvement in professional drivers.
Objectives: The purpose of this study was (1) to document the frequency of drowsy
driving (2) sleep disorders and (3) road accidents among a group of professional
drivers in the regional unit of Iraklion in Crete. Moreover, the study aimed to identify
risk factors that are related to (a) drowsy driving and to (b) road accident risk. Among
the possible factors examined, was the presence of sleep disorders, daytime sleepiness
(EDS), driving characteristics (e.g. driving hours/24 hours, night driving, rotating
shift work schedule), BMI and symptoms of anxiety/depression.
Methods: The study involved 206 individuals from all professional driver groups.
All participants completed a structured questionnaire including data about (1)
demographics and life habits (2) assessment of daytime sleepiness (Epworth scale),
(3) the main symptoms of sleep disorders (PennState Sleep Questionnaire), (4)
drowsy driving symptoms, (5) driving characteristics, data on near-miss accidents (6)
car crashes on the previous 12 months and 3 years (7) anxiety scale (Beck Anxiety
Invertory) and (8) depression scale (Beck Depression Invertory).
Results: Of the 206 professional drivers, 83 (40%) were TAXI drivers, 51 (25%)
urban/intercity bus drivers, 28 (14%) urban bus drivers, 30 (15%) truck transport
drivers and 14 (6%) tourist bus drivers. The majority (n=201, 98%) were male and the
median age was 44 years (23-65 years). The mean BMI was 28.5 ±3 Kgr/m2.. The
median subjective (self-reported) night sleep duration for all groups was 7 hours. 1/3
of the responders sleep during the day (n=59, 30%). Moderate daytime sleepiness (11-
16 ESS) reported on 5.8 (n=12). As for the insomnia symptoms, 17% (n=36) reported
difficulties in falling asleep, 22% (n=45) difficulties in sleep maintenance, 12% (
n=24) reported the subjective feeling that had insomnia. As for the symptoms of sleep
apnea, snoring was reported by most participants (n=125, 61%). Thirty nine
individuals (19%) reported shortness of breath or interruption of breathing during
sleep and 66 (32%) reported having headache while waking, possible sleep related
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sleeping disorder. Participants were also asked about symptoms of narcolepsy, as the
inability to resist to sleep episodes during the day (n=11, 5%), experiences of sudden
loss of control of the body muscles (n=10, 5%) and sleep paralysis (n=5, 2.5%). Of all
the drivers 13% (n=26) had experienced intense drowsiness while driving in the
previous year. Important factors related to drowsy driving was the mean sleep
duration (p=0.03), daytime sleepiness (p=0.006), anxiety (p=0.001) and symptoms of
insomnia (p=0.001). Furthermore, anxiety (β=0.138, CI: 0.06-0.2, p<0.001) and the
average daily working hours (β=0.187, CI:0.014-0.360, p =0.03) were found to
increase the risk of drowsy driving. Considering the driving characteristics, the
overall mean daily driving hours (private vehicle and commercial vehicle) were 7±3
hours and the mean daily working hours were 10 ± 2 hours. The driving experience
was evaluated from the mean years holding the professional driving license (20±9)
and the mean annual mileage (53thous. ± 33thous.). Night driving during 12.00-
6.00am was mentioned frequently in Tourist bus drivers (n=11, 78%) and Taxi drivers
(n=44, 54%). Over half of the participants (125, 60%) worked in shift rotating
schedules. During the past year, 14% (n=29) reported a car crash with slight damage
to the private vehicle and 32% (n=66) car crash with slight damage to the commercial
vehicle. Accidents the severe damage to the vehicle or injury reported in 4% (n=8)
during driving the commercial vehicle and 2.5% (n=5) while driving the private
vehicle. The important factors that were associated with the possibility of accident
involvement were drowsy driving symptoms (p=0.034), daytime sleepiness
(p=0.016), depression (p=0.017), insomnia symptoms (p=0.02) and driving hours per
day (p=0.001).
Conclusions: Drowsy driving and road accidents had been frequently reported in
professional drivers in Heraklio, Crete. Ιnsomnia and sleep apnea symptoms were
prevalent in the study population as well. The main risk factors that were associated
with drowsy driving and road accidents were the increased hours of driving, the short
night sleep duration, anxiety, insomnia symptoms and daytime sleepiness. Therefore,
the implementation of primary prevention activities could target in broadening the
knowledge about drowsy driving, raising awareness on sleep hygiene and the
implementation of safety and occupational health measures in professional drivers.
Secondary prevention could be about early diagnosis and treatment of sleep disorders
that are associated with the impairment of driving performance.
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