Many have been taught from childhood that night air is positively injurious to health, and therefore must be excluded from their rooms. To their own injury they close the windows and doors of their sleeping apartments, to protect themselves from the night air which they say is so dangerous to health. In this they are deceived. In the cool of the evening it may be necessary to guard from chilliness by extra clothing; but they should give their lungs air.... Many are suffering from disease because they refuse to receive into their rooms at night the pure night air. The free, pure air of heaven is one of the richest blessings we can enjoy.—Testimonies for the Church 2:527, 528 (1870).
(CH 59.3)