A plethora of medical consequences have been associated with the syndrome of obstructive sleep apnoea (OSA). These are global, affecting nearly every body function, and have been related to two key pathophysiological findings in sleep apnoea: repetitive falls in oxyhaemoglobin saturation during sleep, and recurrent arousals from sleep which terminate apnoea episodes. Sufferers of OSA may experience daytime sleepiness, which has been measured both subjectively using the Epworth Sleepiness Scale and the Stanford Sleepiness Scale, but also objectively, using Multiple Sleep Latency Testing, Maintenance of Wakefulness testing, and the Oxford Sleep Resistance test. In addition to the loss of alertness, sleep apnoea contributes to memory deficits, reduced vigilance, impaired executive function, increased risk for automobile and occupational accidents, and decreased quality of life.Importantly, afflicted individuals experience improvements in these outcomes with treatment. Taken together, this evidence forms a compelling basis to identify and treat latent cases of sleep apnoea. Not only do patients have the opportunity to achieve improvements in these outcomes and health-related quality of life, but the enormous economic burden that untreated apnoea imposes on the health care system may be eased.