Perhaps no change of fashion in the last fifty years is greater than the change that has come over bedrooms. Fifty years ago the ordinary healthy man (if he could afford it) slept in a deep feather-bed into which his unfortunate body sank and was smothered; his bed was probably draped at the head with large curtains so as to prevent anything like a movement of air getting to him (not that it was very likely, for he kept his windows shut and curtained), while in case of anything so untoward happening he had an additional protection in the shape of a nightcap, while over the whole bed, as likely as not, was a heavy quilt. In fact, the bed gear of fifty years ago was all that bed gear should not be. By degrees the curtains were taken down, the feather mattress was supplanted by a thinner and harder affair which got its elasticity from springs below it, windows were opened, and the nightcap wore out and was not replaced. In fact, the proper rule--the utmost coolness consistent with comfort--came in. The head should be cool, the body not hot nor smothered airlessly beneath masses of coverlets. The feet, however, unless naturally warm, may with advantage have a rug thrown over them; for, if they are warm, proper circulation of the blood is ensured, and a most fruitful cause of insomnia removed. To sum up in one sentence the general principles we have tried to lay down in this chapter, we should say, “When in doubt, open it or take it off”; the point being that you should whenever possible expose yourself to air. Think for a moment of the different _régime_ adopted now, not for people in health, but for consumptives, from what those unfortunates suffered thirty years ago, and think also of the vastly increased percentage of recoveries. Thirty years ago patients were sent to warm enervating places, draughts and cold were treated as if they themselves were the microbes of disease. Now _air_, _air_, _air_, and when the damp and dulness of English winters arrives, up they go into piercing elevations of Swiss mountains. And if air will heal definite disease, we may take it completely for granted that so natural a remedy will be highly beneficial to those in health, for it must and does act as a preventive to disease, and is in itself health-giving. So also with clothing: when in doubt take it off, for the more the skin is either directly exposed or, though clad, allowed to get the maximum possible of air and light, the healthier and the more vigorous it will become; and instead of saying, “Put on a coat, or you will catch cold,” it will be nearer the truth to say, “Continue not to put on a coat and you will not catch cold.” Of course, there are an immense number of days when, especially if one is out in the open air without taking exercise, a coat is advisable, since the feeling of being cold is a natural danger signal, and it is then our business to get warm. But the habit of being cold is often due--and this is our point--to a relaxed and unvigorous