Effects of insomnia and chronic use of hypnotics on driving performance

One of the main problems associated with the use of hypnotics is residual
daytime sleepiness the morning after bedtime administration. This poses a
crucial problem for users of hypnotics whose activity the next morning involves
skilled work and in whom impairment of performance, such as driving a car,
could be a danger to themselves or others. It is, therefore, for the safety of
patients using hypnotics important to have knowledge on the extent of influence
the hypnotics have on their daily activities, particularly driving. Information
on the severity of residual effects of hypnotics is mainly derived from
experimental studies in young healthy volunteers after administration of a
single dose. However, the majority of hypnotic users are elderly (i.e. 55 years
or older) and use hypnotics for longer periods, which may result in tolerance
towards the residual effects. Moreover, hypnotic users have sleep complaints
which may have deleterious consequences on daytime performance. A
hypnotic-induced night of sleep is then expected to improve daytime
functioning, despite the possible sedating residual effects of the hypnotic.

Aim of the study is to investigate what the influence is of insomnia on driving
performance and to what extent this influence is attenuated by the use of
hypnotics.
Therefore, over-the-road driving performance of treated and untreated patients
complaining of insomnia is compared with that of healthy controls matched for
age, gender and annual mileage.

The study will be conducted according to a 3x2 parallel group design with three
groups (users, non-users and matched controles) and two within subject
conditions (habituation and baseline).

Subjects will visit the study centre and be monitored by one of the
investigators for examination during medical screening (2 hours); for training
of cognitive tests and highway driving test (4 hours); and for one habituation
period and one baseline period consisting of an evening, night and following
morning (in total 32 hours, including 16 hours of sleep). Blood samples are
drawn during screening (12 mL) and test periods (8 mL). During test periods
subjects perform cognitive tests and a highway driving test. An on-the-road
driving test has been chosen as it is considered more sensitive than the use of
driving simulators. The latter has been shown not to be sensitive enough to
predict residual drug effects in the on-the-road driving tests of two classical
benzodiazepines.
It is still unclear whether chronic insomnia has significant impairing
consequences on daily life routines such as driving a car. Moreover, it is
unclear whether use of hypnotics can attenuate the presumed effects of
insomnia. In addition it is unknown whether the residual effects hypnotics are
absent in chronic users.
This study is relevant in order to inform patients and physicians adequately on
the effects of insomnia and the possible residual effects of hypnotics, in
particular with respect to their effects on driving performance.
Epidemiological data show some evidence, but the results have not yet been
replicated in experimental studies. Therefore, an on-the-road driving test has
been chosen as it is considered more sensitive than the use of driving
simulators. The latter has been shown not to be sensitive enough to predict
residual drug effects in the on-the-road driving tests of two classical
benzodiazepines. In addition, the current lack of experimental evidence seems
to be a possible result of a lack of ecologically valid tests.