But how much heads-down-eyes-closed-pursed-lipped-cuddly-toy-hugging slumber? You know, sleepy bye-byes. The land of nod. The quality stuff.
Last night, I calculated that my nine year-old stepdaughter had nine hours; my seven year-old son, eight hours; and his four year-old brother around seven.
Yes, the youngest – the one who needs it most – had the least sleep. This is not good parenting. I know that. And the report I read this morning confirmed it.
Researchers at the Autonomous University of Barcelona discovered that children who get less than nine hours sleep a night struggle at school. They assessed 142 primary school pupils and found that most six and seven-year-olds who got less than the allotted time struggled at spelling, grammar and comprehension.
'To innovate and come up with solutions to complex problems, a good night's sleep is essential,' said Professor Russell Foster.
The ideal is between nine and 11 hours a night.
It's hardly rocket science is it: tired kids perform like zombies.
The evidence of which we parents see every breakfast-time.
A few snippets from a typical morning at our house:
'Please take your face out of your cornflakes, son.'
'Brush your TEETH, not your face; and WASH your face, not your teeth.'
'No, no, NO...put your underpants on BEFORE your trousers.'
'Can you PLEASE stop lying on the carpet, I only ironed that shirt last night.'
All of this is down to the fact that they're not getting enough sleep. But achieving that holy grail of at least nine hours a night is much easier said than done when you've got three children of different ages to contend with. Especially this week when we have had something of a perfect storm of counter-sleep circumstances.
This week is my kids' first full week back at school. During the holidays, I didn't mind them going to bed a little later because they were sleeping in a little longer. Now, though, they need to be up with the sparrow's bottom burp and let's put in this way: they're not morning people. It's like having three of the Seven Dwarves in the house – yes, Sleepy, Dopey and Grumpy.
The most worrying impact has been on the youngest. He went into meltdown when he started Reception class and hasn't been the same since. He is normally a real livewire, full of beans and as cheery as one of the other Dwarves. But the step up has really taken its toll.
He is a tyrant to be around, but I know it's all down to tiredness. He spends the evenings rubbing his eyes, but categorically refuses to go to bed before his seven year-old brother who he shares a room with. He's an early-developer victim of that social affliction F.0.M.0. – the Fear Of Missing Out.
Which brings us to the biggest problem: how to stagger bedtimes. It doesn't matter whether you have the child-rearing skills of Supernanny, or the persuasive personality of a UN diplomat, there is no way on earth that you are going to persuade a Tweenage girl to go to bed at the same time as her four year-old brother. It's just soooooo uncool and she might miss out on something, like..I have no idea.
And though it's not as extreme, a seven year-old boy also believes he has an entitlement to stay up that little bit longer than his younger sibling.
So here's how we try to make it work in our family: until 8pm, the kids can do what they like – watch TV, play computer games or even play with each other. And they do, very, very happily.
On the dot of 8pm, it's 'Teeth and Ten' – this means they have to brush their teeth and then they have ten more minutes of play time before bedtime.
All so far, so good. It's when the 'Ten' is up that the Third World War breaks out.
'But why do I have to go to bed at the same time as them?' the nine year-old wails.
'And why do I have to go to bed at the same time as him?' the seven year-old sulks, pointing a disparaging finger at his beloved bro.
The four year-year-old just rubs his eyes, clearly desperate for slumber, but absolutely, catetgorically refuses to give any quarter.
But we are the adults: we are cleverer than them. So we whisper to the eldest that she can read or play on her iTouch for ten more minutes; and we whisper to the middle child that once his brother is asleep, he can have another ten minutes to himself.
And guess what happens: they all try to outdo each other in the staying-awake-and-giggling stakes, flitting in and out of each others' beds and rooms; getting one over on Mum and Dad.
'Be quiet,' we shout. 'Settle down,' we say.
And they just ignore us. For what feels like hours on end. Until, eventually, the nine year-old gets bored and nods off; followed by the seven year-old. By which time, the four year-old is so wired he can't get to sleep at all, and so lies awake staring his glassy eyes at the ceiling, before deciding he wants either a drink or a wee, or both.
So the cycle continues: the bedtime rows; the breakfast time grumps.
Yes, it's bad parenting. Yes, I KNOW they should be getting between nine and 11 hours a night. And yes, I am totally open to suggestions for how to achieve that.
Because I'm too tired to work out the complexities of a solution right now.
Does this sound familiar?
Or have you cracked staggered bed times?
If so, what are your top tips for Keith?