CORRELATION BETWEEN VENTILATION AND EEG-DEFINED AROUSAL DURING SLEEP ONSET IN YOUNG SUBJECTS

In studies of elderly individuals, ventilation and EEG-defined arousal have been shown to vary periodically and synchronously. Such results have been interpreted as indicating the primacy of sleep/wake state in causing ventilatory instability during sleep onset. However, because the elderly individuals studied were periodic breathers, the results d o not unequivocally support this conclusion. In this study the relatio nship between ventilation and EEG-defined arousal was assessed in a gr oup of 21 young, healthy men in whom ventilatory instability during sl eep onset was not periodic. Ventilation and EEG (O-1-A(2)) recordings were collected, and the longest uncontaminated periods from early and late in sleep onset were selected for subsequent analysis. The 84 time series (21 subjects, 2 variables, and 2 occasions in sleep onset) wer e subjected to spectral analysis to identify periodicity, and the rela tionship between the two variables was determined by cross-correlation al methods. The results indicated that the time series were nonperiodi c, yet significant correlations were observed between the two variable s. The data support the view that during sleep onset ventilatory insta bility is driven primarily by variations in sleep/wake arousal level.