Breathing difficulties in women while sleeping are linked to an urge incontinence (over active bladder), according to a new study.

Researchers from the Hospital del Mar in Barcelona, Spain, analysed 72 female patients referred to a sleep disorders clinic with suspected sleep apnea.

All patients completed a questionnaire asking them about four symptoms associated with their bladder control; urgency and frequency of urination, incontinence and nocturia. They were also asked to rate their discomfort with each of these symptoms.

Urge incontinence (or Overactive bladder) is characterised by an increased frequency to urinate along with incontinence and frequent awakening periods during night time to use the toilet (nocturia).

The need to urinate during the night is also a common symptom of sleep apnea, but little research has been carried out to investigate any links between the two conditions.

The new study analysed the questionnaires and 62 of the women were diagnosed with sleep apnea. The people within this group showed significantly higher scores for the prevalence of symptoms associated with bladder control and their discomfort with these symptoms.

Within the group diagnosed with sleep apnea, the symptoms were rated a median average score of 5, out of a possible total of 12, compared to a score of 3 in the group not diagnosed with the condition.

The median average score for discomfort with bladder control symptoms was 4 out of 12, compared with a score of 1 in the group of women who weren't diagnosed with sleep apnea.

"Overactive bladder has a prevalence of 16 per cent among people over 40 years in Europe and it is a difficult condition to live with, affecting a person's quality of life. The findings of this study provide evidence that bladder control could be linked to sleep apnea, although we do not know whether one of the conditions causes the other," lead author, Nuria Grau from the Hospital del Mar in Spain, said in a statement.

The research was presented at the European Respiratory Society's Annual Congress in Vienna.