Physica A. 1998;249:587-93.  

Scaling and universality in heart rate variability distributions.

Ivanov PCh, Rosenblum MG, Peng CK, Mietus JE, Havlin S, Stanley HE, Goldberger
AL.

Department of Physics, Boston University, MA 02215, USA.

We find that a universal homogeneous scaling form describes the distribution of
cardiac variations for a group of healthy subjects, which is stable over a wide
range of time scales.  However, a similar scaling function does not exist for a
group with a common cardiopulmonary instability associated with sleep apnea.
Subtle differences in the distributions for the day- and night-phase dynamics
for healthy subjects are detected.

PMID: 11541514 [PubMed - indexed for MEDLINE]