The Actiwatch Activity Monitoring System relies on the wearing of a very small unobtrusive actigraph unit on the wrist to monitor activity levels (intensity and duration) over set periods to determine sleep-wake episodes and activity profiles. By use of a Windows-based software program, Sleepwatch, predetermined epochs (15 seconds to 2 minutes) can be scored for sleep or wake in periods set by the user. In this way a series of measures for each consolidated sleep episode can be determined.