Younger people excrete most of their fluid before bedtime. The elderly do this during the night. Getting up once or twice at night to urinate can be normal. Injury at childbirth may change the position and effectiveness of the bladder exit tube, the urethra. Once these have been dealt with, the other causes are in the muscle of the bladder, the bladder exit tube, or both.
Bladder incontinence occurs firstly because of storage of urine problems.
Bladder muscle overactivity causes urge, reflex, or mixed incontinence. Secondly, disorders of emptying are caused by bladder muscle underactivity or outlet obstruction, common in men with an enlarged prostate. Both of these disorders can cause overflow incontinence. Many medicines for the heart or high blood pressure relax the muscle in arteries so they relax the bladder muscle or exit muscle too. Muscle deconditioning can affect your bladder as well as your limbs.