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Hum Psychopharmacol. 2008 Oct;23(7):605-13. doi: 10.1002/hup.961.

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

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Faculty of Health and Medical Sciences, HPRU Medical Research Centre, University of Surrey, Guildford, UK.



To assess whether actigraphy is sensitive to benzodiazepine-induced changes in cognitive and psychomotor performance and sleep.


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.


Activity levels were significantly reduced after LZP for 5 h post-dose (p = 0.0104), during sleep (5-13 h) (p < 0.02) and the following morning, 13-14.5 h 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).


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.

[Indexed for MEDLINE]

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