London - By 9pm in our household, all the children - including the grumpy teenager - are safely tucked up in bed. Computers have been shut down, the TV is off and the dog is in her basket, snoring happily. Quite often I’m doing the same under my duvet.

The reason for this is simple. In ten hours we all have to be awake again. In 11 hours I must somehow get four children out of the door and remember a long checklist of things they need for the day. This is not a feat I want to attempt bleary-eyed or with tired, truculent offspring.

Bedtime is the one area of parenting on which I have always refused to budge.

In summer when it’s light outside and the birds are singing, I tape bin bags over the bits of window where the blackout blinds leave a gap and tell them in no uncertain terms to get into bed and stay there until morning.

You may think I am a draconian mother. Indeed, I sometimes feel that Flo, 14, Annie, 12, Monty, ten, and Dolly, three, are the only children in Britain who get a decent night’s sleep. But I know what they are like if they stay up late - by which I mean 10pm - and, trust me, it’s not a pretty sight.

That is why I wholeheartedly applaud Suzanne Morgan, the head teacher at Saltdean Primary School in Brighton, East Sussex, who has written a letter to parents complaining that pupils in her school - some as young as four - often arrive exhausted and seem “ready for bed” by midday.

In her letter, she says teachers are greeted with “tired looks” in the morning, perhaps because children are allowed to have TVs in their rooms.

“We can talk to children about the need for sleep at their age, but we need the co-operation of parents and carers,” she says.

You’d think that any sensible mother would realise this already.

What amazes me is that I know many parents who in every other respect bring up their children well.

They insist on polite behaviour, feed them five fruit and veg a day and insist on limited TV and computer screen time. Yet when it comes to bedtime, all sense flies out of the window.

I’m a sloppy parent in other ways. My children eat frozen pizza too often and don’t always spend long enough on their homework. But when it comes to getting them all horizontal at a reasonable hour, I am immovable.

When they were younger, my motivation was selfish, I admit. With three children under the age of five, my overwhelming desire at 7.30pm was to sit like a zombie in front of Coronation Street in a living room free of primary colours and people under 3ft.

But as they grew older, the tough on bedtime habit remained in place. And thank goodness it did.

At the three schools my children attend, I appear to be a lone soldier on the bedtime battlefield.

Flo is forever moaning that she is the only girl in Year Nine not allowed to watch TV after the watershed, and Monty’s iPad often records Skype requests from classmates at gone 11pm.

Eleven? Are these parents insane? Bedtimes in our house go like this: Dolly lights out at 7pm. Monty lights out at 7.45pm. Annie lights out at 8.30pm and teenager Flo must be in bed - with her smartphone outside her door - by 9pm.

My husband Keith and I remember, as teens, being firmly tucked up by 8pm. We are always repeating the mantra to our children that ‘an hour before midnight is worth two after’. But our offspring are in the minority, as their sleepovers prove.

Like all children, they love bedding down at someone else’s house. Off they’ll go on a Friday night, bagpacked with toothbrush and pyjamas, only to be returned to me on Saturday morning looking like something from Return Of The Living Dead: lank hair, dark shadows under their eyes and lethargic bordering on comatose. It is quite obvious they have had little if any sleep.

“But it’s fun, Mommy,” they protest. “We were allowed to stay up until 3am watching DVDs and eating Haribo.”

I’m sorry, but why is it acceptable to hand back someone else’s child in this state?

Call me a party pooper, but when children come to us for a Friday sleepover, it’s lights out at 10pm.

Needless to say, not many want to kip at the Sibary residence. This is fine by me because I can’t stand over-tired tweens causing havoc and keeping me awake.

Flo’s Facebook logs the time that messages are sent to her, and it seems that half her class are still corresponding past midnight.

I know other children in Monty’s junior school who have TVs in their bedrooms and are allowed to fall asleep at any time they like. Mothers at Dolly’s nursery seem aghast when I say she’s asleep by 7pm.

“But don’t you want to spend quality time with her if you’ve been working all day?” they ask. Er, no, thanks. She needs 12 hours in bed and I need a glass of wine.

Jan Turner, from the Sleep Council, says: “A good night’s sleep is critical for the development and wellbeing of young children. We believe regular bedtimes are vital to achieving this.”

But a recent study suggests that three-quarters of children are not even getting the amount of sleep recommended for adults.

Most sleep for fewer than seven hours a night, so it’s little surprise 79 percent say they can’t concentrate on schoolwork and a quarter admit falling asleep on their classroom desks at least once a week.

You can’t help feeling sorry for teachers. No wonder they are crying out for parents to exercise a little common sense.

Indeed, in her letter, Ms Morgan implores parents to turn off computers and TVs at a sensible time.

“Everyone needs to hear ‘No’ at some point,” she says. As my children frequently do when they try to wheedle their way into staying up.

When should you put your children to bed?

3-4 years 7 pm

5 years 7.30 pm

6 years 8 pm

7 years 8.15 pm

8-10 years 8.30 pm

11-13 years 9 pm

14 years 9.30 pm

15 years 10 pm

16 years 10.30 pm. - Daily Mail