Shift work and Obstructive sleep apnoea (OSA) have been associated with excessive daytime sleepiness and increased risk of road traffic accidents. There is evidence that daytime sleepiness does not provide as satisfactory explanation for accidents, and occupational and social failures associated with sleep disorders. The possibility arises that intermittent hypoxemia and sleep deprivation due to sleep fragmentation in OSA and sleep deprivation secondary to sleep cycle disruption in shift work may underlie neuropsychological deficits, which in turn meditate these functional impairments. The current study uses a control-referenced and norm-referenced design to explore in detail the subcomponents of attention/executive functions and motor coordination of patients with OSA and shift workers with an aim to outline and compare the profiles of any cognitive impairment between these groups.