Abstract: The present invention provides a method of calculating certain body and mental rhythms, and then using this information to indirectly determine the state (flow, body and mental rhythms) which is also reflective of balance between the sympathetic and parasympathetic portions of the autonomic nervous system of the user. By calculating the HRV real time including High Frequency components of the heart information, and for example determining the flow by multiplying the Heart Rate frequency with the Heart Rate Variability, a new method for determining a user state is invented. It is efficient and effective method to use less power within a faster response time for determining such a state. It is applicable in the frequency and time domain.