Estimation of Sleep Quality by Using Microstructure Profiles

Polysomnograhy is the standard method for objectively measuring sleep, both in patient diagnostics in the sleep laboratory and in clinical research. However, the correspondence between this objective measurement and a person's subjective assessment of the sleep quality is surprisingly small, if existent. Considering standard sleep characteristics based on the Rechtschaffen and Kales sleep models and the Self-rating Sleep and Awakening Quality scale (SSA), the observed correlations are at most 0.35. An alternative way of sleep modelling-the probabilistic sleep model (PSM) characterises sleep with probability values of standard sleep stages Wake, S1, S2, slow wave sleep (SWS) and REM operating on three second long time segments. We designed sleep features based on the PSM which correspond to the standard sleep characteristics or reflect the dynamical behaviour of probabilistic sleep curves. The main goal of this work is to show whether the continuous sleep representation includes more information about the subjectively experienced quality of sleep than the traditional hypnogram. Using a linear combination of sleep features an improvement in correlation with the subjective sleep quality scores was observed in comparison to the case when a single sleep feature was considered.