Overflow Incontinence happens when the bladder does not empty completely. Urine builds up and in the end may overflow, often as a frequent, dribbling leakage. You may have difficulty starting to pass urine and the stream may be slower than before.
Stress Incontinence is the most common type of bladder control problem. It has nothing to do with 'stress' in the sense of anxiety. It is nearly always caused by weakness in the pelvic floor muscles.
Urge Incontinence means having a sudden urgent need to pass urine, but not being able to reach the toilet in time. You may also need to pass urine more often than usual (known as 'frequency') and you may wake up several times during the night.
Functional incontinence is the passing of urine in inappropriate places. It may be a result of varying degrees of immobility, for example making it difficult or impossible for the person to reach a toilet or to manage their clothing.
Owing to the extra blood supply to the kidneys at night and the reduced production of the anti-diuretic hormone the elderley can develop nocturnal enuresis.