Leading article: Risky business

It's the final piece in the jigsaw. For years now, scientists have told us that if we don't get enough sleep we are are at an increased risk of a heart attack, stroke, diabetes and cancer. The modern trend for late nights and early mornings is doing us out of the seven to eight hours a night we need to protect our health.

So why, in the face of all that evidence, do we persist with our late nights? Scientists now say that it's not simply the attractions of our 24/7 entertainment culture. A lack of sleep alters the way we look at the world. The more tired we get, the more optimistic we get about danger – playing down the perils or disadvantages of any given situation and emphasising the upside of our willingness to take more and more risks. Lack of sleep doesn't only make us more tired; it also makes us more reckless. Hence the biggest bets are placed in casinos late at night. There's a Catch 22 in that. Science can constantly pile on the evidence that it's dangerous to have less than seven hours of shut-eye a night. The irony is that we'll only believe them if we've had enough sleep.

If we haven't, we'll just tell them to belt up because our hunch is that we'll be perfectly alright whatever they say. Who said science has the answer to everything?