Generally speaking, dry mouth, bitter mouth and bad breath will appear after waking up from sleep and after eating. However, if the bitter mouth and bad breath still cannot be eliminated after brushing teeth, we should be alert and consider whether it is a pathological phenomenon. Reasons for dry mouth and bitterness: 1, when there is disease in the mouth, it may also lead to dry mouth and bitterness, such as mouth ulcers, gingivitis, periodontitis, etc. These diseases may lead to the appearance of the symptoms of bitterness and dry mouth, especially if you do not love to brush your teeth at night, the next day this symptom will be more obvious. 2, if the human body lacks certain nutrients, it will also lead to dry mouth, for example, like the lack of vitamin b2, it will lead to dry mouth situation. In addition to this, there will also be ulcers at the corners of the mouth, dry throat, ulcers on the tongue, so it is very important to supplement vitamin b2 in a timely manner at this time. 3, tension, stress, mood swings, fatigue, irregular life, excessive smoking, alcoholism and so on will cause the phenomenon of dry mouth and bitterness. 4.For some elderly people who have dry mouth for a long time, it is better to have further checkups because some cancers can also cause dry mouth. In addition, there are also some elderly people who suffer from diabetes, because diabetes will lead to the reduction of fluid secretion, it is easy to feel the dry mouth at this time. And the possibility of nocturia is extremely high, making it difficult to make a definitive diagnosis! The main reason for the higher incidence of nocturia in the elderly is advanced age. As for other causes, there are benign prostatic hyperplasia, kidney disease (renal tubular injury, urinary tract infection, etc.), sleep apnea, diabetes mellitus and enuresis, etc. Through clinical data, the increased nocturia in some patients may also be related to menopause, such as dry mouth and drinking more water, and more pronounced nocturia. In summary, there are many reasons why we have dry mouth and bitter and nocturnal urination, when we have these symptoms, we should go to the hospital for a comprehensive examination, we only know the cause of these symptoms, we can find the appropriate treatment to make us healthy.