A local disturbance in the afferent nerves involved in the reflexogenic dilation of the upper airways (UAs) could contribute to the increased collapsibility seen in patients with obstructive sleep apnea (OSA). Laser Doppler perfusion monitoring, combined with electrical stimulation, is a method for investigating the afferent nerve regulation of the microcirculation. It was used in the mucosa of the soft palate in 35 patients with various degrees of UA obstruction and in 13 control subjects, all nonsmoking men. In a majority of snorers and patients with mild OSA, stimulation induced an exaggerated vasodilation, compared with controls. In contrast, in patients with severe OSA, the vasodilation was significantly reduced, compared with controls. These signs of disturbances in the microcirculation support the hypothesis of a local progressive afferent nerve lesion in heavy snorers with or without OSA.