The usefulness of the actigraph methodology has been demonstrated in normal individuals. However, the validity of actigraphy has been questioned in insomnia patients because of the considerable measurement error that has been reported between actigraphy (ACT) and polysomnography (PSG). Two independent investigations have reported errors of 48 and 49 min in total sleep time between ACT and PSG. With a new scoring method called the Actigraph Data Analysis Software, a reanalysis of one of these studies was conducted. Based on this reanalysis, we have obtained a measurement error of only 25 min between the two methods. This finding may be an indication of the advantage of this new scoring method. A strong correlation coefficient (r = 0.82, p < 0.0001) was noted between ACT and PSG for total sleep time, thus suggesting a high degree of accuracy of the actigraph methodology in assessing the sleep/wake profile of insomniacs.