Definition of type of physiological activity and pitfalls of current recording methods

Deliverable No. (use the number indicated on technical annex) Authors (per company, if more than one company provide it together) In numerous studies, physiological signals have been proven to be a sensitive measure for describing human wakefulness and sleep states as well as the transitions between these states. The aim of the current document is to give an overview of the various physiological activities which play a crucial role in monitoring the human sleep-/wakefulness continuum (e.g. brain electrical activity, cardiac activity) on the one hand and fur thermore, to identify additional physiological activities and signals, which are necessary for diagnosing several specific sleep disorders (e.g. respiratory parameters). Accordingly, the methodology currently available to measure these activities (e.g. EEG) is outlined. Special emphasis is put on the insufficiencies of these methods, in order to overcome these shortcomings in future sensor development. Furthermore, thresholds (i.e. the accuracy by which a specific physiological activity has to be measured to adequately reflect a subject's state) was defined to delineate the technical requirements for sensors. Being a part of the EU funded project SENSATION, the current document draws on several sources of information: it is based on a literature search in scientific databases and textbooks, on interviews with experts by means of an electronic questionnaire, and on the results of a brainstorm meeting which was held in Vienna on May 27, 2004. At this meeting, 23 experts discussed limitations of current recording techniques which resulted in a concrete list of definitions and thresholds with respect to physiological data recording, in order to guide further sensor development. The first part of this document deals with the states of sleep and wakefulness as well as their transitions and describes their physiological correlates. Special emphasis is put on the fact, that state transitions might occur either voluntarily or involuntarily. In the second part the changes of physiological activities which are characteristic for specific sleep pathologies are outlined. In the vast majority, patients suffering from sleep disorders differ from a normal population in a multitude of measurable physiological activities. In many disorders, these deviations are even characteristic and specific for a disorder and their objective evaluation is a necessary prerequisite for diagnosis of these disorders. Sleep related pathologies, their characteristic physiological activities described in literature, and the corresponding sensors to measure these activities are summarized in this part. In the third part of this document, dealing with physiological data …