We report a case of a western African man, residing in France for 4 years, who developed human African trypanosomiasis (HAT) caused by Trypanosoma brucei gambiense. Diagnosis was made at a late stage of the disease. The disease was misdiagnosed and untreated for several years because the clinical presentation was limited to psychiatric disorders and biological confirmation was difficult. Polysomnographic recordings demonstrated typical alterations of HAT. Difluoromethylornithine was effective in this late stage of the disease. Magnetic resonance imaging showed brain edema with demyelination and associated brain atrophy and abnormal signals in the brainstem and thalamus, both implied in sleep-wake cycle.