Effects of after-midnight intake of zolpidem and temazepam on driving ability in women with non-organic insomnia

BACKGROUND: Occasionally, insomniac patients may take a sleeping pill after midnight. This may have consequences on their ability to drive a car and result in an increased risk of car accidents. METHODS: This double-blind, randomized, placebo-controlled, three-treatment three-period cross-over study investigated the effects of two frequently prescribed hypnotics of different classes in a real life condition on driving performance and psychomotor skills in insomniac women. Single doses of zolpidem 10 mg (Z), temazepam 20 mg (T) or placebo (P) were administered at 2:00 a.m. to 19 women aged 35-60 years in three treatment periods separated by wash-out periods of 3-14 days. After polysomnography at baseline and each treatment night, patients underwent, 5.5 h after drug intake at 7:30 a.m. on the next morning, a STISIM driving simulator test, and a subsequent neuropsychological test (FePsy). RESULTS: Eighteen insomniac women were included in the analysis (mean age 50 years, mean weight 69 kg, mean BMI 25.6 kg/m2). There were no differences between treatments for the primary outcome measure (mean time to collision; baseline: 0.120 s, P: 0.124, T: 0.118, Z: 0.124; P> or =0.12 for all pairwise comparisons). No differences were recorded for speed deviation and reaction time to tasks for the verum treatments, however, lane position deviation was greater after administration of zolpidem in comparison to both placebo and temazepam (P=0.025 and 0.05, respectively). There were no differences between treatments in the FePsy test. Both medications were well tolerated. CONCLUSIONS: 5.5 h after drug administration there were no major differences in psychomotor performances between both zolpidem and temazepam compared to placebo, which indicates the absence of significant residual effects at that time. However, certain patients were more susceptible than others to the drug effects (two patients with high number of collisions). This underlines the necessity to strongly advocate against the late intake of hypnotics if patients intend to drive a car early the next morning.