The scoring of arousal in sleep: reliability, validity, and alternatives.

The reliability and validity of EEG arousals and other types of arousal are reviewed. Brief arousals during sleep had been observed for many years, but the evolution of sleep medicine in the 1980s directed new attention to these events. Early studies at that time in animals and humans linked brief EEG arousals and associated fragmentation of sleep to daytime sleepiness and degraded performance. Increasing interest in scoring of EEG arousals led the ASDA to publish a scoring manual in 1992. The current review summarizes numerous studies that have examined scoring reliability for these EEG arousals. Validity of EEG arousals was explored by review of studies that empirically varied arousals and found deficits similar to those found after total sleep deprivation depending upon the rate and extent of sleep fragmentation. Additional data from patients with clinical sleep disorders prior to and after effective treatment has also shown a continuing relationship between reduction in pathology-related arousals and improved sleep and daytime function. Finally, many suggestions have been made to refine arousal scoring to include additional elements (e.g., CAP), change the time frame, or focus on other physiological responses such as heart rate or blood pressure changes. Evidence to support the reliability and validity of these measures is presented. It was concluded that the scoring of EEG arousals has added much to our understanding of the sleep process but that significant work on the neurophysiology of arousal needs to be done. Additional refinement of arousal scoring will provide improved insight into sleep pathology and recovery.