Figure 4. The cell groupings that control mood and sleep are very sensitive to caffeine. Animals received increasing acute intravenous injections of 1-10 mg caffeine/kg body wt 15 min before the onset of the [¹⁴C] 2-deoxyglucose procedure. LCMR_glc was measured in the noradrenergic and serotoninergic cell groupings that mediate mood and the sleep-wake cycle: medial raphe (MRAP), dorsal raphe (DRAP), and locus ceruleus (LC). *p < 0.05 and **p < 0.01, significantly different from controls, as determined by Dunnett's t-test for multiple comparisons.