We report a method comprising receiving a first indication to gather a first biological signal or feature thereof from a patient; gathering the first biological signal or feature thereof; receiving a second indication to stop gathering the first biological signal or feature thereof, wherein the second indication relates to a detection of an end of a brain state change; and stopping gathering the first biological signal or feature thereof. We also report a medical device system configured to implement the method. We also report a non-transitory computer readable program storage unit encoded with instructions that, when executed by a computer, perform the method.