Ever found yourself winding down the windows or turning up the music to stay alert while driving? By the time you feel sleepy you may have already had several microsleeps without even realising. Statistics show that fatigue plays a role in 20 per cent of driver fatalities in NSW. Next time you start to feel tired, hand the keys to someone else if you can, or pull over if you can't.

How much do we need? This is a question that still puzzles scientists. The standard· answer is seven to eight hours a night, but the truth is more complicated. As with so many things, our genes largely dictate how much sleep we need and our sensitivity to sleep deprivation. Some people can tolerate large deficits with few problems, while others struggle with the loss of a couple of hours. The key is to know your body and get the right amount of sleep for you.

As if things weren't bad enough, our 24/7 lifestyle could also be making us fat. Studies have shown a negative relationship between body mass index (BMI) and sleep duration-meaning the less we sleep, the higher our BMI. The lack of sleep affects timing of the release of some hormones, including leptin and ghrelin, which suppress and promote appetite respectively. Sleep deprivation may lead to more munching and an expanding waistline. Evidence also suggests that too little sleep increases your chances of cardiovascular disease, type 2 diabetes, respiratory disorders and premature death.