sleep apnoea Repetitive periods without breathing, occurring during sleep, lasting for 10 seconds or longer and recurring hundreds of times a night. Most cases are due to over-relaxation of the muscles of the soft palate, in heavy snorers, which sag and obstruct the airway. Obesity is a common factor. Less commonly, the condition is due to disturbance of the brain mechanisms that maintain respiration. Sleep apnoea is associated with hypertension from over-stimulation of the carotid body by oxygen free radicals and the incidence of heart attacks during the night is three times as high as normal.