Driver sleepiness is known to be a major contributor to road traffic incidents (RTIs). An
initial literature review identified many studies reporting untreated obstructive sleep
apnoea (OSA) sufferers as having impaired driving performance and increased RTI risk.
It is consistently reported that treatment with continuous positive air pressure (CPAP)
improves driving performance and decreases RTI risk, although most of these studies
are conducted less than one year after starting treatment. UK law allows treated OSA
patients to continue driving if their doctor states that treatment has been successful.
Despite the wealth of publications surrounding OSA and driving, 6 key areas were
identified from the literature review as not fully investigated, the: (i) prevalence of
undiagnosed OSA in heavy goods vehicle (HGV) drivers in the UK; (ii) impact of sleep
restriction on long term CPAP treated OSA compared with healthy controls; (iii) ability
of treated OSA participants to identify sleepiness when driving; (iv) impact of one night
CPAP withdrawal on driving performance; (v) individual difference in driving
performance of long term CPAP treated OSA participants; (vi) choice of
countermeasures to driver sleepiness by two groups susceptible to driver sleepiness,
OSA and HGV drivers.
Key areas (i) and (vi) were assessed using questionnaires. 148 HGV drivers were
surveyed to assess OSA symptoms and preference of countermeasures to driver
sleepiness. All participants completing the driving simulator study were also surveyed.
9.5% of HGV drivers were found to have symptoms of suspected undiagnosed OSA.
Additionally the OSA risk factors were more prevalent for HGV drivers than reported in
national statistics reports for the general population. The most effective
countermeasures to driver sleepiness (caffeine and a nap) were not the most popular.
Being part of a susceptible group (OSA or HGV driver) and prior experience of driver
sleepiness did not promote effective choice of countermeasure.
Key areas (ii) to (v) were assessed using a driving simulator. Driving simulators present
a safe environment to test participants in a scenario where they may experience
sleepiness without endangering other road users. (Continues...).
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.