SLEEP ON IT

As Australians adopt busier lifestyles, we're also becoming more sleep-deprived. Emily McCluskey outlines why you may need more zzzzs.

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Sleep deprivation and drowsiness may have been a factor in some of the world's most notable disasters, including the fiery end to the Challenger space shuttle, Chernobyl and the 1988 Exxon Valdez oil spill off the coast of Alaska. If you've ever pulled an all-nighter or been on a sleepless long-haul flight, you'll be familiar with the consequences-grogginess, grumpiness, reduced awareness and forgetfulness. In fact, just 1 7 hours of sustained wakefulness leads to a psychomotor deterioration equivalent to a blood alcohol level of up to 0.05 per cent.

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It's clear we need sleep to maintain normal cognitive functions. But given our increasing tendency to bum the candle at both ends, we're getting less sleep while expecting to achieve more. The truth is you may be sleep deprived without even realising-and the consequences can be amusing or downright dangerous.

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Have you ever misplaced your car keys and found them in the fridge, or put ice cream in the pantry? You may have been the victim of a partial microsleep-a period of involuntary sleeping while still appearing to be awake that can last a few seconds or a few minutes. A new study in rats suggests that when parts of your brain get tired they may go offline to take a nap while you're still conscious. This may be the first sign that your brain needs sleep.

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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.

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If your work is repetitive or requires solving lots of problems, losing sleep is not ideal for your career. Our concentration and thinking ability deteriorate the longer we remain awake; this means decreased accuracy and efficiency. One night of insufficient sleep can result in a 20 per cent-32 per cent increase in mistakes and 14 per cent increase in time needed to perform a task-not great if you're aiming for a promotion or working with heavy machinery.

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Virtually all levels of sleep deprivation adversely affect your mood. Losing a few hours may result in negative mood states, stress, loss of vigour and confusion. Some people even report anxiety, depression and increased moodiness. To keep your friends and family onside, you may need to increase your sleep duration.

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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.

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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.

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At the NYU Sleep Disorders Center, New York City, Dr David Rapoport coordinates the Sleep Research Program. One test they perform has the patient pressing a button every time they see a light flash, to test their alertness and reaction time. Many of his sleep-deprived subjects perform poorly at this exercise-they stop responding and then fall asleep in the chair. While this test may sound quite straightforward, it actually illustrates something very significant. 'We don't fall asleep if we are well rested,' says Rapoport. 'If you're falling asleep in boring situations, that is a sure marker you are not getting quite enough sleep.' So the next time you fall asleep during a dull film, remember this may say more about you than the skills of the director-it could be your body's way of telling you to hit the hay more often.

Source: Choice.com.au