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

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


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 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).

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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anti-Anxiety Agents / pharmacology*
  • Cognition / drug effects*
  • Cross-Over Studies
  • Double-Blind Method
  • Female
  • Humans
  • Lorazepam / pharmacology*
  • Male
  • Motor Activity / drug effects*
  • Neuropsychological Tests
  • Psychometrics
  • Psychomotor Performance / drug effects*
  • Sleep / drug effects
  • Time Factors
  • Young Adult


  • Anti-Anxiety Agents
  • Lorazepam