Disturbed sleep in obstructive sleep apnea expressed in a single index of sleep disturbance (SDI).

The Sleep Disturbance Index (SDI) is a novel index based on polysomnography describing sleep quality in a single score. It was developed and tested with young subjects in the context of research on the effects of noise on sleep. In this study, it is applied in a clinical setting for the first time. A total of 79 patients with suspected sleep apnea received diagnostic polysomnography and the SDI was calculated for these patients. SDI scores in this clinical sample were higher than those of normal young sleepers. They were normally distributed and showed a rather close relationship (r = 0.47) to the Apnea-Hypopnea Indices as measures of disease severity. Patients with more breathing disorders tend to have a higher SDI indicating more impaired sleep. An explorative comparison of SDI scores of this clinical group with SDI scores obtained in noise exposition studies showed higher SDI scores for the patient group. The SDI seems a promising approach to describe sleep in a single score and facilitate comparisons of the effects of, e. g. environmental and medical factors affecting sleep. [ABSTRACT FROM AUTHOR]