A road traffic accident may be the first clear indication of such a sleep disorder. If you know you have uncontrolled sleepiness you MUST not drive. Obstructive Sleep Apnoea (OSA) and Obstructive Sleep Apnoea Syndrome (OSAS) OSAS is a condition which often goes undiagnosed. If it is not fully assessed and treated, this can cause sleepiness and other symptoms which can be a serious risk factor in road traffic accidents.