Reported chronic insomnia is independent of poor sleep as measured by electroencephalography

Objective: Several behavioral, physiological, and subjective variables were examined in subjects reporting chronic insomnia (IN group) and subjects wi th no complaint of insomnia (NC group) to determine factors predictive of p oor sleep as measured by electroencephalography (EEG sleep). Methods: A tot al of 177 subjects (121 in the IN group and 56 in the NC group) were evalua ted on the basis of EEG sleep, subjective sleep, sleepiness, performance, m ood, personality, and metabolic parameters during a 36-hour laboratory stay . Results: Equal percentages of subjects in each group had 0, 1, or 2 night s of poor EEG sleep, indicating that the IN group was not more likely to ha ve impaired sleep in the laboratory. Results of the Minnesota Multiphasic P ersonality Inventory showed that subjects in the IN group had more patholog ical personality profiles, and results of laboratory studies showed that th ese subjects had worse mood ratings, less subjective sleepiness, poorer mem ory performance, and longer midafternoon sleep latencies. Subjects in the I N group also rated their laboratory sleep as poorer in quality with more ti me awake after sleep onset and longer sleep latencies, but no differences i n EEG sleep were observed. Poor nights of EEG sleep were associated with be ing male, increasing age, and a history of more time awake after sleep onse t; among the laboratory tests, poor EEG sleep was associated with worse moo d ratings, poorer memory performance, longer sleep latencies (as indicated by higher scores on the Multiple Sleep Latency Test), higher sleep/wake rat ios for metabolic parameters, lower ratings of sleep quality, and longer pe rceived sleep latencies. Conclusions: A history of chronic insomnia does no t predict poor EEG sleep. Both chronic insomnia and poor EEG sleep are asso ciated independently with dysphoria, hyperarousal, diminished waking functi on, and negative subjective sleep quality. Separate arousal and sleep syste ms are posited to account for these results.