We study the possibility to synchronize cardiorhythm of a human by periodic
and aperiodic sequences of light and sound pulses. Aperiodic forcing is de
fined by variation of RR intervals of another subject. Phase locking betwee
n cardiorhythm and weak external forcing is detected on finite time interva
ls. We observe the 1 : 1 synchronization for periodic forcing and II : m sy
nchronization for aperiodic one.