Abstract
The effect of psychoactive drugs on sleep is traditionally evaluated with polysomnography (PSG) whereas daytime effects are conventionally assessed with psychometric tests to measure changes in daytime cognition and psychomotor functioning. This thesis examines whether the actigraph, a non-invasive tool, that records rest-activity patterns has the ability to measure drug-induced changes in daytime activity patterns and in sleep. Two studies were designed to assess the acute effects of psychoactive drugs on daytime activity levels and sleep in a controlled laboratory environment with healthy participants. In the first study participants were randomised to a double-blind, placebo-controlled, crossover trial with lorazepam (LZP), a benzodiazepine sedating hypnotic. Actigraphic activity levels were significantly reduced following LZP dosing (2. 5 mg) and these changes were reflected by impairment of cognitive and psychomotor performance. Participants in the second laboratory study were randomised to a double-blind, placebo-controlled, crossover trial with the sedating antihistamine promethazine. Reduced activity levels reflected changes in significant impairment of cognitive and psychomotor performance. Actigraphy therefore appeared to be sensitive to acute sedating effects and was able to detect changes in sleep behaviour. Since antidepressants are only effective after chronic administration the effects of treatment was investigated in a third field study. Depressed patients were randomised to a doubleblind, parallel group, multi-centre, 14 week study of the antidepressants paroxetine, fluoxetine or sertraline, including abrupt discontinuation. Activity was recorded continuously throughout the whole study. Significant improvement in patients’ subjective mood scales, as depression was alleviated, was reflected in changes in actigraphic sleep and activity profiles. The findings provide an indication of the usefulness of actigraphy as a diagnostic tool to measure psychoactive drug-induced changes following medication. Further work should concentrate on standardising procedures, study design and algorithms. Actigraphy may thus be a useful sensitive tool in assessing the psychopharmacology of psychoactive medication.