Residual effects of benzodiazepine and non-benzodiazepine hypnotics on diurnal attention in a reaction time task

The residual effects of benzodiazepines on attention and psychomotor perfor mance have been extensively documented. However, there are very few studies comparing the action of benzodiazepines and non-benzodiazepine (imidazopir idines and cyclopirrolones) compounds on these parameters. The aim of this work was to assess the residual effects on diurnal wakefulness in healthy v olunteers after nocturnal administration of a single dose of diazepam (10 m g), zolpidem (10 me), zopiclone (7.5 mp), gamma-amino-beta -hydroxybutyrate (500 mg), or placebo. Drugs were given at 22 h (half-hour before bedtime), in a double-blind fashion according to an extended Youden Square design. S ubjects slept for six consecutive nights in the sleep laboratory (habituati on, baseline, drug 1, placebo, drug 2, placebo). The morning after nocturna l dosing, psychomotor performance was measured using a simple visuomotor re action time (RT) task, with two stimulation patterns (isochronus and stocha stic). The results indicated an absence of residual effects on attention af ter zopiclone and zolpidem intake. Likewise. administration of diazepam did not provoke a significant deterioration in the attention level. GABOB was the only drug which produced a marked decrease in the isochronus RT after 9 hours of its administration, in comparison to its baseline, not appreciati ng any significant modification in the stochastic RT. It is emphasized that residual impairment on RT following intake of hypnotics should be consider ed on thr basis of the stimulation pattern used (stochastic vs isochronus) during vigilance assessment.