Sunshine and fresh air as health factors important to the restoration of sick people back to health have been well known for hundreds of years, and therefore no further discussion about them will be needed. It also goes without saying that rest should be adequate.

A full dissertation on the importance of direct natural sunlight and the benefits to be derived from not excessive exposure to natural ultraviolet light energy is given in the Chapter "Natural Light and Health" in The Health Revolution, if a deeper understanding of the physiology involved is desired.