Twovolved in the demonstration of sleep hypoxemia in patients with cystic fibrosis. First, the degrees of arterial oxygen desaturation presently shown by Francis et al (see p 734) may be great enough to accelerate the progress of cor pulmonale. Second, disturbance of the normal sleep pattern is a problem recognized by patients with advanced pulmonary disease. It certainly worsens their quality of life and may well hasten the course of the disease itself.
Relationships between sleep state and breathing are now studied with great interest by researchers in respiratory physiology, neurophysiology, and anesthesiology. New techniques allow meaningful descriptions of sleep state, activity of respiratory muscles, mechanics of breathing, and changes in arterial blood gas levels. However, the pertinent questions arose from clinical observations. Adults with severe chronic obstructive pulmonary disease have long been known to suffer reversal of the normal sleep pattern; they have increasing wakefulness at night and somnolence