1. A method comprising: transforming a EEG signal to the frequency domain with a Discrete Fourier Transform, obtaining the amplitude of each frequency component, summing all of the amplitudes of each frequency component to obtain a total amplitude, summing all of the amplitudes of frequencies in the range of 201-500 Hz to obtain a high frequency amplitude, summing all of the amplitudes of frequencies in the range of 1 to at least 15 Hz to obtain a low frequency amplitude, and calculating an Index based on the total amplitude, the high frequency amplitude, and the low frequency amplitude.