difficulty (whatever its cause), and upon returning to bed I can generally rely upon getting two or three hours of most refreshing sleep."
It can, however, do no harm to combine an air-bath with a few minutes of indoor exercise. Perfect freedom of motion is, indeed, incompatible with the restraint of artificial teguments, and the effect of Dr. Franklin's prescription could generally be improved by gymnastics tending to stimulate the action of the respiratory organs. During sleep the blood is only imperfectly oxidized, and an accumulated deficiency of that sort (indicated by choking fits) is one of the most common causes of interrupted slumber.
The solaria, or sunbath-rooms of the ancients, probably served a similar purpose. Stoves and chimney fires—though not unknown—were rare in Athens, and in Rome were considered a prerogative of wealth; the great plurality, even of well-to-do citizens, survived the winter under a load of cumbersome garments, and now and then retired to a solarium to give their skins a chance for direct contact with the circulation-stimulating atmosphere.
