IT'S NOT often I need an alarm clock to wake me up. Like many 'mature' people, I rarely sleep much beyond eight. That's in the winter. In the summer, I wake even earlier.

During the shortest nights, when it hardly gets dark, there's a curlew that starts calling outside our house at about three in the morning. To me, that's one of the loveliest sounds on earth, so I'll lie and listen to it, soothed and refreshed, before drifting off to sleep again. After all, I don't generally need to get up at three and you can't set a curlew to go off when you need it.

Sometimes, though, I have to be sure to get up early - to catch a train, because someone's coming to service the boiler, for a hair appointment... And since you can't rely on having a handy curlew with an exact sense of timing around when you need it, I have to set my alarm clock. It's a little travelling alarm with a persistent electronic beep, designed to drive you mad if you don't turn it off quickly.

There are many different kinds of alarm clock. Some make a pleasant enough noise but just aren't loud enough. Some switch on the radio, which would only make me inclined to linger in bed listening to it, so I've never had one of those. Then there's the Teasmade - do they still make them? They used to be a favourite for retirement gifts, which always seems a bit odd since one of the best things about retirement is supposed to be not needing an alarm of any kind.

We did have a Teasmade once, as a substitute for one of us having to get up early to make two cups of tea. But it wasn't a success. A human being tiptoes downstairs, does all the noisy clattering things far off in the kitchen and brings the tea to the bedside in silence or with a gentle greeting.

The Teasmade was a bit like having a grumpy old man in the room. It would start making a spluttering, hissing noise long before you needed to wake, so that by the time the tea was ready you'd had quite enough and fled to the peace of the bathroom. So, after a few goes we stopped using it. For years it just sat there gathering dust, until at last we took it to a charity shop.

What no one seems to have invented yet is a personalised alarm - one that plays the sound of your choice, waking you exactly as you'd like to be woken. I know what I'd choose if they did invent one: the sound of my grandson waking up. Not when he was a tiny baby, of course. As every parent of a new baby knows, they're designed to work like alarm clocks - they make a horrible noise that you can't possibly ignore and have to do something about as quickly as you can.

No, I'd have the sound of Jonah waking up, aged two and a bit. I've shared a bedroom with him, so I know exactly how it goes. First, around seven in the morning, there are little snatches of song: Baa, Baa Black Sheep, then a bit of Twinkle, Twinkle Little Star. Now and then, there's Happy Birthday to You (they sing that quite a bit at nursery). After a while he stops singing to check up on the toys in his cot, My Big Bear (that's the hot water bottle cover he likes to rest his head on); My Po (the red Teletubby his aunt - my daughter - gave him for his second birthday); My black cat (self explanatory). He shuffles them about, plays with them, talks to them.

Ten minutes or so of that and he decides it's time someone else was around. Thump. 'My Po!' This time he speaks in the tone of someone saying 'Fetch!' to a dog. It's much the same idea really: he wants an adult to come running and pick up Po and (more especially) him. If the response isn't quick enough, then it's: 'My Nana!'

I haven't discovered what happens if you ignore that call, because I've always answered it. There's no panicky fumbling for the switch-off button, desperate to stop the horrible bleep, yet it's every bit as much of an irresistible summons, one that cannot be denied.

And what alarm clock rewards you with a pair of arms round your neck and a laughing, chattering weight in your arms? What alarm clock eases you so happily into the purposeful bustle of the day?

So, if anyone comes up with that kind of personalised alarm, just let me know. I'd happily wake to those sounds every day.