For better health it is recommended to breathe through your nose. Do this during the day and during the night. If you are finding this difficult to do you may be able to do this over time with practice. Start to notice when you have your mouth open and close it when you notice it is open. If you have congestion you may find that you unconsciously open your mouth in order to breathe. If you practice closing your mouth you may notice that by breathing gently in and out of your nose, your congestion begins to clear. Congestion is also sometimes caused by inflammation. Sometimes the cause of inflammation is the foods you are eating. In particular sugary and starchy foods are known to cause inflammation. Try eating less of those types of foods and also drink more water.
I am mouth breather. I have been for a long time. It may be too late for me to reverse it because my face has taken a shape that makes it more challenging to keep my mouth closed. But I have noticed that since I have been practicing keeping my mouth closed I am seeing great benefits. I am experiencing less jaw pain now than when I left my mouth open. Sometimes I sleep with some tape on my mouth in order to help me to sleep with my mouth shut. Sometimes I find I sleep better that way. It is a work in progress for me.
It is best to breathe in and out through your nose. Keep you mouth closed and your lips sealed. Keep your tongue pressed up in the roof of your mouth. You may be able to change the shape of your face by doing this. You may be able to create more space in your mouth for your tongue and teeth. This can be very beneficial in the long run.
“I, who have seen some thousands of Indian women giving the breast to their infants, never saw an Indian mother withdrawing the nipple from the mouth of a young infant, without carefully closing its lips with her fingers. I was soon made to understand, both by their women and their Medicine Men, that it was done ‘to insure their good looks and prolong their lives.’ It is to Mothers, and truly not to physicians or medicines, that the world are to look, for the remedy of this evil (of mouth breathing) and the physical improvements of mankind, and the prolongation of human existence, effected by it.” From Shut Your Mouth and Save Your Life written by George Catlin, in 1890