AbstractOver the last 25 years wrist actigraphy has predominantly been used in sleep research and chronobiology where the technique has proved useful in the measurement of sleep and the characterisation of the sleep/wake cycle. Whilst there are a large number of studies published that have used actigraphy, there have only been relatively few studies that have shown that the technique is capable of measuring drug‐induced changes in nocturnal and/or diurnal behaviour. Thus the use of actigraphy to measure drug effects in clinical trials has up till now remained on the periphery of psychopharmacology. However this may be because of the disparate nature of the studies published rather than lack of usefulness. This paper reviews the relevant literature and in doing so concludes that there is a convincing body of evidence for the utility of actigraphy as a technique in human psychopharmacology. Copyright © 2003 John Wiley & Sons, Ltd.