THE UNDERSTANDING OF INSOMNIA REQUIRES THE EVALUATION OF MULTIPLE COMPONENTS SUCH AS NIGHTTIME SLEEP , DAYTIME FUNCTIONING

THE UNDERSTANDING OF INSOMNIA REQUIRES THE EVALUATION OF MULTIPLE COMPONENTS SUCH AS NIGHTTIME SLEEP, DAYTIME FUNCTIONING, AND VARIABILITY IN SLEEPWAKE PATTERNS.1 Several assessment tools have been developed over the years to assess these components. Polysomnography (PSG) is considered the gold standard for the objective assessment of sleep, whereas the sleep diary is a standard procedure used for the subjective assessment of sleep.1 Polysomnography provides an accurate measure of wake and sleep time, as well as of sleep stages. However, it is an expensive approach, and its ecologic validity is sometimes questionable. The use of a daily sleep diary is particularly useful for evaluating sleep over extended periods of time in the patient’s home environment.1 It also has the advantage of providing a measure of night-to-night variability in sleep-wake patterns; however, the accuracy of the sleep diary is entirely dependent on the patient’s perception.2 Therefore, objective assessment tools that are accurate, more accessible, and more economical than PSG for evaluating sleep in a natural environment are needed. Wrist actigraphy was designed as an alternative assessment device to gather objective data on sleep-wake parameters (see Sadeh et al3 for more details). The actigraph is a small watch-like device that records movements. It is worn all night, typically on the wrist of the nondominant hand. The presence of movement is interpreted as time awake, and the absence of movement as sleep time. The actigraph has the advantage of being a nonintrusive tool for assessing sleep in a natural environment. In spite of this advantage, its accuracy and clinical usefulness for assessing insomnia is still equivocal.3 An adequate evaluation of the accuracy of actigraphy should be based on comparisons of same-night recordings of PSG and sleep-diary data. To be useful, actigraphy data should yield data convergent with PSG measures and be more accurate than the sleep diary.4 Of the studies that have investigated the accuracy of actigraphy, 5 have used, actigraphy and sleep-diary data that were not obtained from the same nights as the PSG recordings.5-9 Only 2 studies10,11 have reported results on these 3 measures obtained from the same nights. Five studies compared actigraphy to sleep diary alone,7,12-16 and 3 studies9,10,13 evaluated actigraphy’s sensitivity to treatment response. These studies indicate that, depending on the participants’ insomnia diagnosis (eg, psychophysiologic or sleep-state misperception), actigraphy underestimates13 or overestimates total sleep time (TST)6,10,17 compared to PSG. The agreement coefficients between PSG and actigraphy for detecting TST vary from . 818 to . 8817 and are lower than for good sleepers (above 90%3). The magnitude of the discrepancies between those assessment devices varies from 25 minutes5 to 49 minutes.6 Regardless of the direction of the discrepancies, actigraphy has been found to be sensitive to treatment effect.9,10,13 Moreover, data on time in bed (TIB) suggest that actigraphy is a reliable measure of adherence to behavioral treatment procedures.9,13 Despite technologic improvements and innovations in recent years,11,18,19 the accuracy and clinical usefulness of actigraphy in the assessment of insomnia is still controversial. Discrepancies may result from the inclusion of subjects with sleep-state misperception, a factor that can contribute to the underestimation of sleep time,6 or the use of heterogeneous samples comprising subjects with other sleep disorders or coexisting psychologic disorders.17 The paucity of studies using multiple PSG and parallel nights of actigraphy and sleep-diary recordings of sleep makes it difficult to understand these discrepancies. There is, therefore, a need to compare PSG, actigraphy, and sleep-diary data collected for the same nights of sleep and on more than 1 night using a homogeneous sample of insomnia patients both before and after treatment. The present study further evaluates the accuracy, sensitivity, and clinical utility of actigraphy in documenting treatment response in chronic insomnia. Polysomnography, actigraphy, and a sleep diary are used for a total of 4 nights, including 2 at baseline and 2 after treatment.