Something smells funny, silver lights flash, an ache starts to grow, and another migraine headache begins its (usually) inexorable course. Sufferers like Dr. Brainard should look into his brief compress of clinical studies, informed speculation, and personal history, which identifies the triggers and prescribes avoidance measures. Dilation of the brain's blood vessels is thought to be the source of pain, responsive to the drug ergotamine if caught early, proceeding through miserable stages if not. Dr. Brainard notes the association with fatigue and stress (which cause physiological changes) but also insists emphatically on other mechanisms which can be anticipated and regulated: salt intake, chemical ingestion (MSG, alcohol, tyramine), food allergies and low blood sugar, physical factors (high altitude, early season sun). Migraine patients diagnosed by a physician (to rule out conditions which mimic the symptoms) who wish to try his regimen will find it demanding--limited nights out, closely watched diet, lots of sleep, precise work and vacation conditions--but relief may be its own compensation.