I was watching a programme about time on BBC4 last night in which a professor was discussing major scientific breakthroughs of the past century.

Scientists now realise that, contrary to what we've always thought, time is not a constant. I might have got this wrong, but apparently the faster something travels, the slower time passes when observed by a third party.

Scientists also say that time travel is -- theoretically, at least -- possible. All that stands in the way of us being able to travel back in time is the engineering.

Yes, I know, hard to get your head around. (Just watch a few episodes of Doctor Who for a recap.) I was mulling all this over at 1am this morning, sitting bleary-eyed with baby Matthew in the crook of my arm and a bottle of formula milk protruding from his lips.

I just wish the science engineers would hurry up and build a time machine. I could do with going back and catching up on a few hours' sleep.

Louise is breast-feeding Matthew at the moment, but she goes off to bed at about 11am to grab some much-needed rest, while I give Matthew a bottle of formula milk.

It's actually working quite well as Matthew slept until 3.30am before Louise had to get up and feed him.

It's amazing how the body adapts to a lack of sleep. I'm at my desk at the Guardian office this morning working on pages for this week's paper and although I've only had a few hours' kip, I actually feel pretty good.

I usually feel drained at about three in the afternoon, however, and that's when I do a raid on the chocolate in the Guardian's vending machine.

I suppose that, and copious amounts of strong coffee are a parent's best friend.