  The average wavelet coefficient method is applied to investigate the scaling
features of heart rate variability during meditation, a state of induced mental
relaxation. While periodicity dominates the behavior of the heart rate time
series at short intervals, the meditation induced correlations in the signal
become significantly weaker at longer time scales. Further study of these
correlations by means of an entropy analysis in the natural time domain reveals
that the induced mental relaxation introduces substantial loss of complexity at
larger scales, which indicates a change in the physiological mechanisms
involved.
