1. A method for determining the appropriate dosage of a medication to treat Attention Deficit Hyperactivity Disorder (ADHD) in an individual who has ADHD comprising: measuring the stress of a human subject by sampling the peripheral skin temperature of a human subject during a predetermined time interval when the subject is in an inactive state to provide sampled peripheral skin temperature data; analyzing the sampled peripheral skin temperature data for a pre-selected parameter to determine whether said pre-selected parameter has a value indicative of ADHD; and determining the proper dosage of a medication to treat ADHD based upon said determined value of said pre-selected parameter; and at a time subsequent to administering said dosage, determining if the administered dosage of medication is actually effective at removing the effects of ADHD as measured by said pre-selected parameter.