SEVERE snoring may be a cause of impotence in men because it interrupts normal sleep patterns, claims a private clinic. Dr Christine Vesselinova-Jenkins, of the London Clinic, says sleep apnoea, when breathing stops temporarily, shortens the dreaming stage - the period when the male hormone testosterone is produced. Lack of oxygen caused by apnoea also reduces testosterone levels. Treating sleep disturbances may help men with erectile failure, she suggests.