Healthy sleepers are rare: problems and success rates in establishing a control group for sleep studies

A large and representative control group is paramount for establishing normative values for sleep in middle-aged persons. However, it is very difficult to recruit normal sleepers. From 286 volunteers who responded to an advertisement for healthy sleepers, only 47 finished the study. We excluded 221 after evaluation of their medical sleep history, general health data, and results of physical examination. We further excluded 18 volunteers after nighttime polysomnography. We finally eliminated from the study 37.5% of the volunteers who entered the screening procedure, on grounds of their sleep disturbances. Our study reveals that investigators face major difficulties when trying to establish a control group of healthy sleepers from the middle-aged population. Sufficient interest on the part of potential test persons does in fact exist, but their general health-and, especially, previously undiscovered sleep disorders-frequently prohibit their inclusion. International and interdisciplinary cooperation is necessary to establish a sufficiently large control group for both clinical and research purposes.