Myths of sleep

5 February 2013

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Sleep is fundamental for the body to function, so how much sleep should we really be getting each night?

According to the National Institute of Neurological Disorders and Stroke (NINDS), the optimum amount of sleep for most adults is seven to eight hours each night.  However a sleep census has discovered that Australian’s feel short-changed when it comes to sleep, on average missing out on two weeks of sleep each year.

The topic of sleep is a foggy one, with many myths surrounding the issue, so we had a chat to sleep expert, Dr Moira Junge, to see if she could help clear the air.

Dr Junge is the Chairperson of the Australasian Sleep Association’s Insomnia and Sleep Health Special Interest Group. She currently works at the Melbourne Sleep Disorders Centre as a registered psychologist and has a doctorate in health psychology.

Myth one: Sleep debt is a real concept.

‘There is indeed such a thing as sleep debt and most of our society is carrying one around with them, particularly during the working week. To pay back one’s sleep debt, you don’t necessarily catch up in terms of hours, more in quality.’

Verdict: true.

Myth two: Exercising late at night won’t affect our ability to sleep because it will tire us out.

‘For sleep to occur we need to have had the message  sent to our brain that it is dark and then melatonin is secreted.  As the levels of melatonin rise, our core body temperature drops and sleep onset follows.’

‘However, if there is vigorous exercising late at night then the core body temperature remains elevated. You need a couple of hours after the exercise has ceased and core body temperature has been able to drop to get sleepy naturally.’

Verdict: false

Myth three: Lack of sleep can cause weight gain.

‘A growing body of epidemiological evidence supports an association between short sleep duration and the risk for obesity and diabetes, due to a decreased glucose tolerance, which leads to changes in insulin sensitivity.’

‘Regulation of appetite is also affected when there is sleep loss, as levels of the hormone, leptin, are decreased, whereas the levels of ghrelin are increased. These hormone changes are correlated with increased hunger and appetite, which can lead to overeating and weight gain.’

‘It can also simply be that the longer you’re up, the more chance you have for loading calories into your body, and the more tired you are, the less likely you are to be doing regular exercise.’

Verdict: true

Myth four: Dreaming only occurs in the last stage of REM sleep.

‘Eighty per cent of our dreaming occurs during REM sleep but some can occur in non-REM sleep, like stage two.’

Verdict: false

Myth five: Exposure to artificial light before bed makes it more difficult to get to sleep.

‘Melatonin is secreted naturally in our brain via the pineal gland at night, in response to darkness. Depending on how bright the artificial light is, this can suppress melatonin and prevent the natural sleep form occurring at the natural time.’

‘Moreover, the stimulation from screens such as iPhones, laptops, iPads, PCs, etc. is implicated in people becoming too alert and over-stimulated. It’s a combination of the artificial light impacting on the natural sleep rhythm, and the stimulation from the various technologies that is keeping people up.’

Verdict: true

Jacinta Young is a Bachelor of Journalism student at La Trobe University. You can follow her on twitter: @jacinta_007.