Benzodiazepine-induced reduction in activity mirrors decrements in cognitive and psychomotor performance

Objective To assess whether actigraphy is sensitive to benzodiazepine-induced changes in cognitive and psychomotor performance and sleep. Methods Healthy young volunteers (n = 23; 11 males), were randomised to a double-blind, placebo-controlled, crossover trial. Actigraphy was used to record motor activity continuously. Following dosing at 18.00 h with 2.5 mg lorazepam (LZP), psychomotor and cognitive assessments were made at hourly intervals post-dose for 4 h and after sleep at 14.5 h post-dose. Results Activity levels were significantly reduced after LZP for 5h post-dose (p=0.0104), during sleep (5-13h) (p<0.02) and the following morning, 13-14.5h post-dose (p<0.02). At the same time cognitive and psychomotor performance was also significantly impaired (p<0.05). LZP also significantly increased actigraphic sleep efficiency and sleep per cent (p<0.02). Conclusion This study showed that activity levels were significantly reduced following dosing with a benzodiazepine and these changes coincided with impairment of cognitive and psychomotor performance. Actigraphy, therefore, appears to be able to reflect the psychopharmacological effects of a benzodiazepine in changes in daytime function and nocturnal behaviour, which, without waking the subject, is beyond the power of conventional psychometrics. Copyright (C) 2008 John Wiley & Sons,