Progressive aging does not alter the interaction between autonomic cardiac activity and delta EEG power

Objective We tested the hypothesis that the reductions of the changes in the respective influence of the cardiac sympathetic and vagal activity control and delta EEG activity with aging alter the interactions between the heart rate variability (HRV) and the delta sleep EEG power band. Methods A polysomnography was performed on 16 healthy young men and 19 healthy middle-aged men across the first 3 NREM–REM cycles. Spectral analysis was applied to electrocardiogram and electroencephalogram recordings. High Frequency (HFnu) of HRV as well as the maximum of cross-spectrum, coherency, gain and phase shifts between HFnu and delta sleep EEG power band were compared between both groups. Results Young men experienced more deep sleep than middle-aged men (P<0.001). In middle-aged subjects, HFnu was lower than the HFnu of their younger counterparts (P<0.001), but they showed similar increases during NREM sleep and similar decreases during REM sleep as the young subjects. Cross-spectrum values, coherency, gain and phase shifts between HFnu and delta were identical between the two groups. Modifications in HFnu show parallel changes and precede changes in delta EEG band by a similar leads of 11±6 min in young men and 9±7 min in middle-aged men (P=0.23). Conclusions Reduced changes in the respective influence of the cardiac sympathetic and vagal activity and delta EEG activity with progressive aging do not alter the relationship and phase difference between changes in the relative predominant cardiac vagal activity and delta power in middle-aged men. Significance Interaction between the cardiac sympathetic and vagal activity with delta EEG activity is maintained in middle-aged men.