Method for monitoring brain activity. Left and right cardiac pulse signals are detected at bilateral locations on a body for a selected number of cardiac cycles. Computing apparatus computes the standard deviation of the left and right pulse signals for the selected number of cardiac cycles. The standard deviations are normalized on the computing apparatus by dividing the left and right standard deviations by the mean of the left and right pulse signals computed over the selected number of cardiac cycles to produce a left and a right Coefficient of Variation of the pulse signals. A Bilateral Pulse Index is generated from the left and right Coefficients of Variation. The Bilateral Pulse Index relates to brain activity. Cardiac pulse signals from a single location on the body may be utilized in some embodiments.
