12 noon: Wake
1.30pm: Turn on computer
6.30pm: Hear one or both parents return from work and rush into shower, slamming door
7pm: Make 'snack' while parents trying to cook
7.30pm: Go out
From 9pm onwards: Text one or both parents to say that on way home
In what feels like the middle of the night: Slam front door, turn on lights, eat another 'snack'
1am: Turn off TV
In the summer holidays, the average parent's timetable goes like this:
6.30am: Get up to go to work
6.30pm: Return from work
From 9pm onwards: Text 'Where r u?' to son or daughter
The rest of the night: Slump on sofa or in bed, continually jolted awake from fitful doze by loud noises (front door slamming, crash of crockery in kitchen, etc) or sudden shock (all landing lights suddenly turned on)
Average number of hours per day that teenager spends asleep = 11
Average number of hours per day that parent spends asleep = 5
I'm not sure I've got the maths right. But I'm too tired to work out where I've gone wrong.