According to my literature, the sympathetic nervous system accelerates heart rate and modulates < 0.1 Hz, whereas the parasympathetic nervous system decelerates heart rate and is modulated 0.04 - 0.5 Hz.
According to this, heart rate accelerates in sympathetic which means the frequency should be higher than that compared to Parasympathetic. Though Parasympathetic starts with 0.04 it goes up to a value higher than 0.1Hz. Why so?
Here is the source (Physiological Sensing of Emotion by Jennifer Healey in the Oxford Handbook of Affective Computing):
Since it is known that the parasympathetic nervous system is able to modulate heart rate effectively at all frequencies between 0.04 and 0.5 Hz, whereas the sympathetic system modulates heart rate with significant gain only below 0.1Hz (Akselrod, Gordon, Ubel, Shannon, & Cohen, 1981; Berntson, et al., 1997), the relative strengths of the sympathetic and parasympathetic influence on HRV can be discriminated in the spectral domain.
