Poster presentations

Abstract

Introduction: Actigraphy has grown in popularity as an additional measure of sleep behaviour in recent years. The extent of its role in sleep medicine is unclear, perhaps due to the low temporal resolution of commercial measurement systems available. Such systems typically monitor only a single location and do not record data synchronised with PSG systems meaning that temporal correlation between eventsobserved in other channels and actigraphy is difficult to ascertain. Further, conventional actigraphy records only summarised activity counts, implying that morphologically different movements may result in the same or similar activity counts. The aim of this technical case study was to directly compare data recorded using a Continuous Multisite Accelerometry System (CMAS) to an Actiwatch (TM).Method: A male test subject wore an Actiwatch MiniMotionlogger (TM) on the left wrist, and the CMAS with accelerometers located on left wrist and middle fi nger, left ankle and great toe, and the sternal notch for an overnight sleep period.Results: A number of interesting features were identifi ed including (A) Movement recorded on ankle and toe, in absence of movement from other channels indicating a kick of that leg; (B) Movement recorded on finger in absence of wrist movement indicating a finger twitch; (C) Movement in all accelerometry channels with a change in posture; and (D) Series of movements recorded only in toe accelerometry channel.Discussion: CMAS was able to identify and characterise subject movements, which were not able to be differentiated using the Actiwatch (TM). The multisite nature of the system detects movements which are not observed on Actiwatch.