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Obesity and Sleep Apnoea

Obesity is the strongest risk factor for obstructive sleep apnoea (OSA). Approximately 60% of moderate-to-severe OSA is due to obesity. Other risk factors are increasing age, male gender, perimenopausal or postmenopausal status in women and craniofacial abnormalities (eg, a slightly backwards displaced lower jaw or overbite).

However there is evidence for a bi-directional relationship between obesity and OSA with recognition that the development of OSA and its subsequent sleep fragmentation may contribute to accelerated weight gain.

  • Many patients report rapid increases in weight in the year prior to OSA diagnosis
  • Data shows sleep deprivation states are associated with increases in appetite hormones
  • Sleep deprivation states result in altered eating patterns, including a preference for calorie-dense foods

Untreated OSA and obesity may create a vicious cycle of increased OSA and obesity, unless patients are properly managed.


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Comorbid Insomnia and Sleep Apnoea


Obstructive sleep apnoea (OSA) and insomnia often coexist - a comorbidity known as COMISA.

Studies show a high overlap between the two conditions.

Traditionally, the two conditions have been viewed as distinct entities; however, they may be interrelated.

It is important to consider both in patients who present with sleep problems.

Several symptoms are common to both conditions, including non-restorative sleep, frequent awakening and fatigue.

All patients with insomnia should be screened for OSA, and insomnia should be considered in all patioents diagnosed with OSA.

COMISA is more challenging to treat than either disorder presenting alone, and therapy is generally guided by the presenting compliant and/or predominant complaint.

PUBLISHED: Australian Doctor GP Journal 6 April 2020

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What you eat can help you sleep (or not)


The recommended, but often elusive, seven to nine hours of restorative slumber can seem out of reach of many.  In 2019, the Australian Sleep Health Foundation found that more than half of Australians reported suffering from at least one chronic sleep symptom ranging from having difficulty falling asleep, waking too early or being unable to get back to sleep after being disturbed.

When it comes to proactively managing our sleep, avoiding screens is a common recommendation but far less frequently do we hear about the impact of diet on sleep quality. A closer look at the science suggests that our diet can impact our sleep, and vice versa, in a number of different ways.

What she ate last thing at night could have an impact on how much of this she gets.

What she ate last thing at night could have an impact on how much of this she gets.

If you have ever been told to try a glass of warm milk before bed, there is some science that suggests this could indeed help you get to sleep. Protein-rich foods including milk, turkey, eggs and fish, as well as leafy greens and nuts, contain the amino acid tryptophan. In the body, tryptophan is converted into serotonin and melatonin, the hormone that helps to maintain the sleep, wake cycle. As such, consuming foods rich in tryptophan within an hour or two of sleep should aid the process.

Avoiding caffeine is another common recommendation. Found in a wide range of foods including chocolate, cola drinks, coffee, and tea including green tea, the stimulatory effects of caffeine can be experienced for several hours after consumption. While individuals can have vastly different tolerance levels, if you are sensitive it is suggested you avoid all caffeine for several hours before you plan to hit the sack, including those squares of dark chocolate.

There is also some evidence to suggest that processed foods, in particular processed meats are associated with sleep issues. A small study published in the American Journal of Lifestyle Medicine found that of 104 patients recently diagnosed with obstructive sleep apnoea, those who were overweight and who ate a diet high in fat had sleep apnoea twice as severe as others. In addition, there was a specific association between processed meat consumption and sleep apnoea severity.

"There some evidence to suggest that processed foods, in particular processed meats are associated with sleep issues."

Although diet and sleep have been the subject of many studies, Sleep and Respiratory Physician Dr Anup Desai, from Sydney Sleep Centre says we do need to be careful with the conclusions drawn from many of these studies. "Food and sleep is a difficult topic, as the studies tend to be relatively small and of low scientific rigour. They do not provide clear evidence of a significant clinical effect on our sleep," he says.

"There are some general guidelines, such as avoiding caffeine and for those with obstructive sleep apnoea, avoiding alcohol. It also appears that high fat and high sugar diets are not helpful when it comes to sleep. Perhaps most importantly though is the effect a lack of sleep has on our food choices the next day."

There are multiple studies showing a lack of sleep is associated with increased portion sizes and higher calorie snacking the next day. In turn, this potentially impacts our health and weight control, long term, which in turn can impact sleep.

"There are multiple studies showing a lack of sleep is associated with increased portion sizes and higher calorie snacking the next day."

One study published in the Journal of Neuroscience investigated the relationship between sleep quality and subsequent snacking behaviour. It looked at the dietary habits of 32 healthy men who were fed a healthy dinner and snack before bed, before half the group were sent home to sleep while the other half were kept awake all night. The next morning participants had their hunger and appetite assessed, their desire for chocolate bars rated and a brain scan completed.

It was found that while both study groups rated similar hunger the next morning, their desire for chocolate was much greater when sleep-deprived, they had higher levels of the hunger hormone ghrelin and their brains used more energy when they were tired. Researchers concluded that this potentially explains why we are more tempted by treat foods when we are sleep deprived.

It is not only adults whose dietary patterns need to be considered when it comes to sleep. Paediatric Respiratory and Sleep Medicine Physician, Dr Jasneek Chawla from Queensland Children’s Hospital regularly consults with children battling sleep issues and sleep apnoea, he advises people to strive for a regular mealtime routine and advise to avoid high-sugar confectionery which can be associated with poorer sleep quality.

"We also encourage children to avoid heavy meals before bedtime but most importantly our role is to make parents aware of the associations between sleep and obesity. Studies suggest that shorter sleep duration is associated with an increased risk of obesity in children and adolescents. Additionally, the risk of breathing difficulties during sleep, such as obstructive sleep apnoea, are much greater in obese children," he says.

For Dr Desai, one of the most powerful things patients can do when seeking to improve their sleep is to give attention to it. "As a society we are busier, eat later, eat more processed foods and use more screens. Ultimately diet, exercise, weight and sleep are all connected so if we are to be successful at improving one, we need to work on all in unison," he says.

And worst case, you can always try that glass of warm milk.


AUTHOR: Susie Burrell is a dietitian and nutritionist.

PUBLISHED: Lifestyle Section 27/02/2020


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Professor Matthew Walker

Professor Matthew Walker is a Professor of Neuroscience and Psychology at the University of California, Berkeley, and Founder and Director of the Center for Human Sleep Science. This podcast provides lots of interesting insights in to the importance of good sleep. It focuses largely on sleep restriction or sleep deprivation and how this has broad impacts on human health.

  • Global sleep loss epidimic - the average American sleeps only 6.5 hours per night
  • Sleep has slowly been eroded by our society over the last 60 years
  • Sleep is vital and essential from an evolutionary standpoint - you can’t just lop off 25% of the necessary sleep you need 
  • Studies across millions of people show one clear thing - the shorter your sleep, the shorter your life
  • If you sleep less, you will be dead sooner, lack of sleep kills your more quickly
  • Lack of sleep is a major predictor of “all cause mortality” including cancer, alzheimers, heart disease, stroke, diabetes, depression, and suicide
  • Hard science shows why a lack of sleep is tremendously bad for you
  • Sleep has an image problem, we stigmatize sleep and think its lazy and slothful - people wear lack of sleep as a badge of honor to be celebrated
  • Less sleep does not equal more productivity 
  • The 5 clear truths of sleep research and productivity
    • Under-slept employees take on less challenging problems
    • They produce fewer creative solutions
    • They exert less effort when working in groups (slacking off, social loafing)
    • They are more likely to lie, cheat, and engage in deviant behavior
    • The more or less sleep that a CEO has had, the more or less charismatic they will be
  • Chronic exhaustion cost most first world nation 2% of the GDP - 411 billion dollars lost each year to a lack of sleep
  • The research is very clear that under-slept individuals are not as productive or successful 
  • The evidence is resoundingly clear - cutting on sleep makes you less productive and less creative and less effective
  • After being awake for 21 hours, you’re as cognitively imparied as someoen who is legally drunk
  • The two principle types of sleep - REM sleep and non-REM sleep
  • The different stages of sleep - the 4 stages of REM sleep
  • Hard science shows that deep Sleep is critical to clearing toxins out of your brain
  • Sleep is like a sewage system for your brian - it cleans all the toxins and debris out of your brain
  • The less sleep you have, the higher your probability of getting alzheimers
  • Different cognitive systems in your brain also work during sleep - its like saving files to a hard drive, you have to sleep to get the save button
  • The emotional circuits of the brain are changed and modified by sleep - the amygdala (which controls fight or flight) is regulated by the prefontrol cortex
  • Lack of sleep can have a serious negative impact on your emotional health 
  • Sleep reboots body systems as well - not just the brain
  • Deep sleep is one of the best blood pressure medications you can imagine
  • Deep sleep regulates insulin levels and blood glucose levels
  • Sleep is also essential for the reproductive system 
  • Sleep boosts testosterone and lack of sleep makes you 10 years older from a testosterone standpoint
  • Apetite, weight, food consumption are all regulated by sleep - lack of sleep makes you eat 300-550 more calories per day, and makes you eat more high sugar and high carb foods
  • Sleep also has a profound impact on the immune system - one night of 4 hours of sleep will drop natural killer cells (body cancer fight cells) by 70%!
  • The link between lack of sleep and cancer the WHO recently classified night shift work as a probable carcinogen
  • Sleeping 5 hours per night makes you 200-300% more likely to catch a cold than someone sleeping 8 hours a night
  • There is not a SYSTEM or PROCESS in the body/brain that is not impacted by sleep
  • The most striking omission in the health literature today is that sleep is not at the center of the health conversation
  • 3 key ways sleep improves your learning
  • Is it wise to pull an all nighter? What does the research say?
  • The “memory inbox of the brain” (hippocampus) and how sleep is vital to creating and storing memories
  • Sleep is vital both BEFORE learning and AFTER learning to store and save new memories and solidify them into the architecture of the brain
  • Sleep replays information and strengthens memories
  • Sleep provides a 3x advantage to problem solving compared to an equivalent period being awake 
  • "The 6 Unpopular Tactics for Getting Enough Sleep"
    • Carve out enough time and make sleep a priority - carve out an 8 hour window to sleep every night
      • This is the #1 thing to do - regularity is KEY - go to bed at the same time and wake up at the same time, no matter what
      • Sleeping in late creates “social jetlag” which has serious negative consequences - regualirty of sleep is key
    • Keep the temperature cool - keep your bedroom 68 degrees - your body needs to drop its core temperature 2-3 degrees to fall asleep
      • You can hack this by taking a hot bath before bed
    • DARKNESS is key to producing melatonin. Phones, screens, blue light etc trick the brain into thinking its day time and shut off melatonin production
      • Reading on a tablet 1 hour before bed shifts your melatonin production 3 hours later!
      • Use blackout shades
      • No screens 1 hour before bed
    • Do NOT stay in bed if you’ve been in bed longer than 20 minutes. You brain is a very associative machine - being awake in bed trains the brain that its OK to be awake in bed. Get up, go to a different room, read a book in dim light, no screens, no eating. And only when you feel sleep return to bed, and you will re-learn the key association between making teh bed about sleep
      • Some people don’t like this idea. 
      • Meditation is a great way to get yourself to fall back asleep. The studies are very clear, very well done that meditation can help improve sleep. 
    • No caffeine after noon and avoid alcohol in the evenings. 
      • Caffein prevents deep sleep 
      • Alcohol fragments  your sleep and makes your wake up much more, leaving with unrestorative sleep
      • Alchohol blocks dreams and REM sleep 
  • Sedation is NOT sleep. Knocking out your cortext is not natural sleep. 
  • You could be A FAR BETTER VERSION OF YOURSELF mentally, cognitively, physiology if you just got more sleep
  • Current sleeping pills are “sedative hypnotics” that do NOT productive naturalistic sleep, and do not get the benefits of sleep
  • Sleeping pills have a far higher risk of death, cancer, infection
  • CBTI - cognitive behavioral therapy for insomnia is just as effective as sleeping pills in the short term, but much more effective long term
  • Melatonin can be a useful tool to time the onset of sleep
  • Does napping work?
  • There is no such thing as the sleep bank - you can’t accumulate a debt and then hope to cash in on the weekend - sleep doesn’t work like that
  • Napping can prevent you from falling asleep and staying asleep! Be careful!
  • How does GABA impact your sleep?
  • Sleep is a remarkably complex neurochemical ballet

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