Sleep, sleep disturbance and daytime sleepiness in normal subjects

The concept of sleep disturbance is rather vague. Many people claim to suffer from sleep disturbance, but yet find it hard to describe exactly what they mean by the label in subjective terms. Sleep researchers have a similar problem, it is difficult to describe what is meant by sleep disturbance either in an objective or a subjective way, and harder still to relate sleep disturbance to sleepiness shown the following day. [Continues.]