1. A method of treating insomnia in a patient in need of such treatment, the method comprising: applying noninvasive, regional brain cooling to a region of a patient's head over a forehead and a temporal region of the patient's skull to locally cool the patient's forehead and the patient's temporal region by applying a temperature of between 10° C. and 28° C. prior to sleep, wherein the patient has insomnia and wherein applying comprises circulating a temperature-controlled fluid through an applicator on the patient's head; and maintaining the temperature between 10° C. and 28° C. to reduce brain metabolism in one or more of the patient's frontal cortex, prefrontal cortex and temporal cortex; and allowing the patient to fall asleep.