Changes in oxygen saturation and heart frequency during sleep in young normal subjects.

Changes in oxygen saturation and heart frequency were measured during sleep in a group of 21 normal subjects (9 women and 12 men) aged 19-25. At the time of the investigation all were non-smokers, they had no respiratory complaints, and indices of lung function (lung volumes, volume-pressure diagram, and diffusing capacity for carbon monoxide) were within normal limits. In contrast to published data, there were no major changes in oxygen saturation and no differences between men and women.