New parents face up to six years of disrupted sleep, the results of a new study indicate.

European and US researchers studied the sleep of almost 4,700 parents who had children between 2008 and 2015.

They found that the birth of a child has major short-term effects on sleep, especially among women.

"Sleep satisfaction and duration sharply declined with childbirth and reached a nadir during the first three months postpartum, with women more strongly affected," they noted.

During that first three months, mothers slept an average of one hour less than before pregnancy, compared to 15 minutes less for fathers.

"Women tend to experience more sleep disruption than men after the birth of a child reflecting that mothers are still more often in the role of the primary caregiver than fathers," commented Dr Sakari Lemola of the University of Warwick in the UK.

However, parents' sleep was still being disrupted when their children were aged between four and six years, with mothers experiencing 20 minutes shorter sleep duration during this period, and men experiencing 15 minutes less.

The researchers found that sleep disruption was a bigger issue for first-time parents compared to experienced parents. It also tended to be more of an issue during the first six months for breastfeeding mothers compared to bottle-feeding mothers.

"While having children is a major source of joy for most parents, it is possible that increased demands and responsibilities associated with the role as a parent lead to shorter sleep and decreased sleep quality even up to six years after birth of the first child," Dr Lemola concluded.

Details of these findings are published in the journal, Sleep.