A scale for the estimation of sleep problems in clinical research

Problems in sleeping are widely prevalent in modern society and are often one of the presenting complaints of patients consulting physicians. In addition, there is scattered epidemiologic evidence and considerable clinical support that disturbed or inadequate sleep may be a risk factor for clinical emergence of cardiovascular disease and for total mortality. The role of sleep problems both as a precursor and as a sequela of disease states could be better delineated in large groups by the availability of a brief, reliable and standardized scale for sleep disturbance. Such a scale could also be used to evaluate the impact of different therapies upon sleep problems. This paper presents data from two study populations responding to three and four item self-report scales. From 9 to 12% of air traffic controllers reported various sleep problems to have occurred on half or more of the days during the prior month, whereas 12-22% of patients 6 months after cardiac surgery reported such frequent sleep problems. Utilizing data from the 6 and 12 month follow-ups, test-retest reliability of the three-item scale in cardiac surgery patients was found to be 0.59. Internal consistency coefficients for the three and four-item scales were 0.63 and 0.79 respectively.