Hi Guys,

If you still are interested in finding an algorithm that works, it is described in that paper.
It is an increase in the chaotisity that you are looking for (decrease in D2 degree of freedom)

Good luck ! ^^

PS : I can't post links so here is the references :

Nonlinear analysis of continuous ECG during sleep II. Dynamical measures
J. Fell, K. Mann, J.Roschke, M. S. Gopinathan
Department of Psychiatry, University of Mainz, Untere Zahlbacher Strasse 8, 55101 Mainz, Germany
Department of Chemistry, Indian Institute of Technology, 600 036 Madras, Chennai, India
Received: 7 June 1999 /Accepted in revised form: 10 December 1999