Since I had my fourth baby four months ago, I honestly can't remember having had a proper night's sleep - in fact, up until a few weeks ago, I felt on the verge of losing my mind. Everyone will tell you that newborn babies wake up all the time, which they do. They have to, they need to eat. Everyone will tell you that it's hard but what no one tells you is just how this lack of sleep will make you feel. For me, it's as if someone has dropped a boulder on my head. My eyesight is constantly fuzzy, my head aches, I am bad-tempered, I look dreadful, my self confidence plummets, I scream at my other children ... I am, in short, a walking disaster zone.

So I wasn't at all surprised to read about a new survey, commissioned by Mother & Baby magazine, which showed that mothers survive on an average of just three-and-a-half hours' sleep a night for the first four months of their baby's life - with a third getting even less than three hours. The fallout from this sleeplessness is hardly eyebrow-raising either: half the respondents said that the sleeplessness had caused rows with their partners, 13% that it had almost led to them splitting up, and 3% that it had actually laid waste to the relationship entirely. And 83% said that sheer fatigue put them off sex, with 94% of mothers saying that they would rather go to sleep on hitting the sack than do anything else.

So far, so predictable. What did surprise me, though, is that new mothers are now getting just half the amount of sleep our own mothers got when we were babies. They would typically get a lavish six hours, which seems to point towards a pretty seismic cultural shift.

Why should this be? The report pinpoints a change in attitudes to child rearing, particularly the prevalence of products such as baby monitors and cot mattresses fitted with alarms (in case the baby gets too hot or too cold). In fact, 74% of respondents had "two-way baby alarms", 19% had invested in "breathing sensors" and 12% had set up "video monitors of baby in the cot" all of which has probably contributed to the creation of a generation of more fretful, and, consequently, wakeful mothers.

That said, I am not sure whether the contraptions represent the chicken or the egg in this equation. When I had my eldest child Raymond - a screamer if ever there was one - 11 years ago, I didn't have any of the baby-listening contraptions that are available today. He slept - or rather didn't sleep - in bed with me and his father so we didn't need any listening devices. Neither of us actually slept, though. I was so paranoid about Raymond suffocating under the duvet, that I insisted we had it constantly at half-mast. As he was a winter baby, his father and I spent the night quietly freezing.

Once Raymond had moved into his own room at about six months old, I decided I would just put him to bed, shut the door and be done with it. If he was really crying, I reasoned, I would hear him.

As the nights went on, though, I found myself fretting constantly. Even when everything was silent, I'd be convinced Raymond was crying and, in the end, in order to get some sleep, I decided to get a baby monitor. But then I spent nights shaking it, bashing it and straining to listen into it as I would decide it was too quiet in Raymond's room and maybe he wasn't breathing. OH GOD, HE'S DEAD! I would think, before rushing to him in a panic and waking him up.

I complained to my mother that I was exhausted, and she simply said, "No one ever died from a lack of sleep," before putting Raymond in his pram, marching him to the bottom of the garden and leaving him there. He slept happily and soundly for three whole hours.

Our parents probably do know something about babies that my generation seem to have missed. They know that babies are hardy little creatures who are pretty good at getting what they want, when they want it. Responding to the survey, older women's suggestions for new mothers wanting to catch up on sleep included letting the baby cry for longer (45%), investing in a dummy (40%) and giving up breast-feeding (33%), all of which would be considered fairly controversial in the current parenting climate.

The other interesting finding is that fathers are getting plenty of shut-eye in those early months of baby's life - an average of seven hours, in fact. Of those surveyed, 55% said that they "hardly ever or never" got up to attend to the baby in the night, while 23% said that their baby's cries didn't rouse them.

Which makes sense to me. My husband, while offering most wholeheartedly to help during the night, has managed to sleep through night feeds, nappy changing, crying from babies and other children, and wakes up feeling, if not fresh as a daisy, then a damn sight more refreshed than I am. In fact, with this last child, we gave up on the pretence of shared night-care entirely. He left the marital bed and is currently camped out in the study. I actually don't mind this because: a) he snores, so when I do eventually finish changing and feeding the baby now, I'm no longer greeted in bed by a cacophony of deep grumbles, and b) it gives me a get-out clause with the other children. I hear him in the morning when they are clamouring to see me. "Mummy's asleep," he yells. "ASLEEP! I am making you breakfast!" And, to give him his due, it is not as if he can breast-feed the baby twice a night. What he can and does do is take over most of the care of the other children during the day.

Actually, my fourth baby is beginning to sleep very well. I had her in bed with me - as I have had all of them - but about a month ago she started pushing me away. Eventually my husband suggested she moved into a cot in the room next to ours. Even though my baby is merely a piece of chipboard away, though, I feel I am always half awake. I can never switch off from her.

Maybe this is the difference between generations of women and also between men and women. These days mothers tend to rank their children's needs higher than their own. I feel my baby's happiness is utterly vital to her and consequently, to me. I have always found it almost impossible to leave a crying baby. Women of an older generation say things like, "You're making a rod for your own back," whenever someone picks up their baby as soon as they start crying. But I cannot help it. I am programmed this way and I am not sure if fathers are. When my baby cries, every bone in my body wants to comfort her even if she has only done one second of crying. It's different for my husband. If he is in the middle of making the boys their dinner and the baby cries, he just makes kissing noises at her but carries on with what he is doing. "The baby's crying!" I'll scream at him. "Pick her up!" But he'll say, "I'll pick her up when I've mashed the potatoes."

There will be an end to it, though. That's what I tell myself. And then, believe me, I am going to try my hardest to claw those sleep-hours back. With four children, though, I fear I may have said goodbye to them forever.