Sleepless, you drive as if you'd been drinking

In 1997, two Australian researchers, Drew Dawson and Kathryn Reid, measured something unsettling: how performance deteriorates as the hours without sleep pile up. Then they compared it with the effect of alcohol on the same people.

The result is worth remembering. After about 17 hours awake —from getting up to midnight— coordination and reflexes drop to a level similar to having 0.05 of blood alcohol, exactly the legal driving limit in Spain. And after 24 hours without sleep, the impairment matches nearly 0.10: clearly drunk.

The dangerous part is that tiredness doesn't feel like a drink. Nobody takes your keys away for having been awake too long.

So driving at dawn after a full day on your feet isn't just 'being tired': it's getting behind the wheel with the reflexes of someone who's been drinking.