The effect of Adrafinil, unlike conventional stimulants, builds subtly over a period of days to months. This appears to be based on its ability to selectively stimulate adrenergic receptors in the brain. These receptors normally respond to norepinephrine
J Clin Psychiatry 2000 May;61(5):378-81 Modafinil augmentation of antidepressant treatment in depression. Menza MA, Kaufman KR, Castellanos A Department of Psychiatry, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical Sch