Having a baby does affect a good night's sleep for mothers more than fathers, despite the rise of the modern man willing to share parental responsibilities, a new study suggests. Researchers also discovered that experienced mothers suffer more than first time mums, for sleep quality gets worse with each new child while for fathers, it makes no difference. And it may be down to the men not pulling their weight, health experts said, because as a couple have more children the lack of help from dads increases the tension and stress in the mothers. It is not just the amount of sleep in hours and minutes that is affected, but the number of times it is interrupted and the quality of sleep, according to the study published in Journal of Sleep Research. Researchers at Montreal's McGill University analysed the sleep patterns of 54 couples with children and three single mothers every night for two weeks. First time mothers suffered fragmented sleep. But while second or third time mums had more experience in dealing with a crying baby, their quality of sleep worsened - though the time spent asleep remained the same. However, for fathers, their overall night time sleep patterns remained unchanged both in length and quality whether they were father to one crying baby or multiple children over the years.