New parents can lose two months-worth of sleep in the first year of their baby's life, a survey has suggested.
Broken sleep can be tiring for all
The poll of 500 mothers and fathers showed a third lose 90 minutes sleep per night, equating to a full night's sleep every week, or 68 in a year.
And almost half of new parents argue over who has less sleep, with mothers claiming they lose the most.
Midwives said the problems, exposed in the survey by nursery products company Tomy, affect first-time parents most.
This "competitive sleep syndrome" can strain relationships, the survey suggested.
Nearly half of the new parents said they argued with their partner over who has less sleep.
A total of 42% of mothers claim they respond to their baby's night-time cries within 30 seconds, while 68% say their partner takes five minutes or longer.
Only 1% of women claim to be able to sleep through their baby's cries but 43% claim their partner can.
A fifth of parents said they were woken four times a night or more with their baby in its first month.
By the age of one, 38% of babies are still not sleeping through, while 15% of parents with one to two year olds are still experiencing disrupted sleep.
Although some of the new parents said they found the experience liberating, because it made them realise they needed less sleep than they previously thought they did, most claimed their experience had left a permanent legacy.
Over half (57%) said they were now a lighter sleeper as a result of listening out for their baby and 11% said they had had problems with sleep since being parents.
A quarter said the experience had put a strain on their relationship with their partner.
Joanne Gray, of Tomy said: "Being up with a screaming baby, several times in the night can be a very lonely experience, especially if you're not getting support.
A thing that parents did find helpful was establishing a bedtime routine for their baby - such as a bath and story time.
Mervi Jokinen of the Royal College of Midwives said: "Sleep problems are more common for first-time parents. You have to get to know your baby and gain confidence."
She said there was support available, from midwives and from local community support groups for new parents.