Neuropsychological function and sleep in the aged have been studied for more than 20 years. The elderly studies focused on psychometric correlates of sleep architecture (REM, SWS, and various measures of sleep disturbance). More recently, psychometrics have been related to breathing disturbance in sleep, but the interpretation of such deficits in terms of hypoxemia and sleepiness remains controversial. To a large extent, all such relationships may depend upon the medical risk factors and chronic conditions affecting both neuropsychological function and sleep in old age.