Aspects of driving after hypnotic therapy with particular reference to temazepam

In a double-blind study, 32 outpatients with sleep disorders received oral doses of temazepam 20 mg (n= 16) or flunitrazepam 2 mg (n= 16) once a night for 7 days. On the morning after the first and seventh doses, patients completed psychomotor tests and a real driving test on the road over a 25 km course. The road test included a 1 km straight stretch driven at constant speed. In the car, various parameters were automatically recorded every second for approximately 60 minutes. These included angular velocity of steering, lateral acceleration and velocity. An optimization quotient, a measure of the efficiency of information processing in the driver-vehicle-road interaction, was derived from these parameters. An observer recorded driving performance by scoring standardized tasks. After a single dose of temazepam, the improvement in driver performance as shown by a decreased optimization quotient was significantly different to the deterioration seen after flunitrazepam (p < 0.05). After the seventh dose, this trend was still apparent but was not statistically significant. After both one and seven doses, the angular velocity of steering was significantly decreased in the temazepam group compared with an increase after flunitrazepam (p < 0.001). Over the straight, this deterioration in steering ability in the flunitrazepam group was apparent after one dose and reached statistical significance compared with temazepam after seven doses (p < 0.01). After both one and seven doses, drivers in the temazepam group made fewer errors in the technical handling of the car whereas drivers in the flunitrazepam group made slightly more errors. This difference between the groups was statistically significant on both days (p < 0.05).