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New light on body clocks and sleep

Highlights from Sydney Ideas

Most of us know that getting a good night’s sleep is important for our health and wellbeing but achieving quality sleep isn’t always easy.

Someone who genuinely understands the importance of sleep is journalist and presenter, Fran Kelly who spent 17 years hosting Radio National’s breakfast program. We were delighted that Fran could lead a Sydney Ideas discussion with three leading sleep researchers, and we’ve included some of the highlights of the talk and a few tips from our experts.

Sleep is also really key for the plasticity of our brain and some of these processes we know are involved in mental health conditions like depression and anxiety.
Dr Jacob Crouse, Brain and Mind Centre

The restorative function of sleep

Dr Jacob Crouse, Postdoctoral Researcher at the Brain and Mind Centre

Dr Jacob Crouse is a Postdoctoral Research Fellow with the Youth Mental Health and Technology team at the Brain and Mind Centre – part of a major youth mental health project who had their results of their research published in The Lancet. He describes sleep as ‘A kind of housekeeping of metabolic waste that builds up throughout the day.’

‘Sleep is also really key for the plasticity of our brain and some of these processes we know are involved in mental health conditions like depression and anxiety. A lot of these processes are really key and the frontal regions of our brain where we have these higher order cognitive processes that are engaged in anxious thinking; sleep is really important for rejuvenating these processes,’ said Dr Crouse.

What happens when we sleep?

Professor Sharon Naismith, neuropsychologist

Professor Sharon Naismith, a clinical neuropsychologist at the Charles Perkins Centre who also heads the Healthy Brain Ageing Program at the Brain and Mind Centre, described what happens during the sleep process and the importance of a good night’s sleep to brain health. 

‘There are so many different things that sleep does in the brain and all of those hours are keeping our brains healthy,’ she said.

‘Sleep actually occurs in 90-minute cycles. We start off awake and then go into very, very light sleep and then gradually go into deeper stages of sleep, until we get into a really nice, deep restorative sleep which we call that slow wave sleep, and that part of sleep is particularly important for restorative processes, for laying down new memories, for flushing the brain out of different toxins. And then we cycle back up,’ she said. ‘The electrical activity in the brain actually changes a lot while we're sleeping and that coincides with those different sleep stages that we're in.'

One big problem is that our modern environments have so much light in them, that they actually suppress melatonin.
Associate Professor Sean Cain, Monash

Circadian rhythms and body clocks

Associate Professor Sean Cain is an expert in circadian rhythms at Monash University and President of the Australasian Chronobiology Society. His lab focusses on the individual differences in sensitivity to light and how not getting enough light at the right time of the day can lead to sleep disorders, metabolic disease and depression.

‘We've got this bossy master clock at the base of our brain, and it orchestrates the rhythms throughout the brain and body. You've got loads of clocks in your brain, loads of clocks through virtually every bit of tissue in your body, and they all want to keep a certain time,’ he said.

‘Every night, your body produces the sleep promoting hormone melatonin, so it's telling your body it's night-time and you start to sort of relax and get a little bit sleepy. It occurs over several hours.'

Associate Professor Sean Cain, circadian rhythm expert at Monash University

'One big problem is that our modern environments have so much light in them, that they actually suppress melatonin. We did a study in Australian homes and found that about half homes have enough light all the way up to bedtime to suppress about half of that melatonin, so it makes it very hard to get to sleep; and in fact, it tricks your clock into thinking it's actually still daytime.’

Tips for a better night’s sleep

The right light

According to Sean Cain, there are two things that can make a difference to our circadian rhythms and the quality of our sleep.

‘One thing that can really boost sleep is avoiding light at night and getting lots of bright light in the day,’ he said.  ‘If the sun is out, go and get some light. If the sun is not out, avoid light.’

His second recommendation recognises that our busy lives mean that getting the right amount of natural light isn’t always possible.

‘Get smart lights.’ he said. ‘Smart lights can change their hue so that they can be brighter white and blue. That's fine during the day, you want them as bright and blue as possible. But they can also change to more of an orange kind of candlelight colour, and you can make them go very, very dim.’

Take care of your mental health

Jacob Crouse recommends engaging in mental health boosting behaviours to enable healthy sleep patterns.

‘I think bringing together some of these things that we know are associated with good mental health - being physically active, socialising with people and getting exposure to light during the daytime - and trying to do all these things at the same time, could have a really positive effect on how we sleep and the rhythmicity of our circadian rhythm.’

Seek treatment for sleep disorders and keep your mind and body active

Sharon Naismith recommends treating sleep disorders to maintain brain health, particularly as we reach middle age.

‘One big one is sleep apnea – so snoring, daytime sleepiness – look out for those. Go talk to your doctor, there are a gold standard treatments for it. We know that sleep apnea starves the brain of oxygen, it fragments our sleep a lot, but it can be treated.’

She also recommends physical and cognitive workouts.

‘Physical activity, resistance training and aerobic activity have both been shown to improve our slow wave sleep – so how deep we go into that state – that's when our brain is clearing all the toxins out in that nice deep, slow wave sleep,’ she said.

‘Just because we get older doesn't mean we have to keep doing the same thing. Keep the brain active, learn new skills, learn new languages, change your job, get more complexity in it, and stay socially connected. All of those things are important for keeping our brain active.’


To find out more, watch the full event or listen to the podcast from Sydney Ideas here.

Article by Susanna Smith for Sydney Ideas