Why do we need sleep?

Sleep has a profound effect on brain function and is critical for the growth of new brain cells and formation of new connections. Getting adequate sleep helps with memory and learning, particularly in the way it allows our brains to filter out and store the important bits of information we have gathered throughout the day and store these to memory.

Our brains also use sleep as an opportunity to flush out toxins that have accumulated throughout the day. Some of these toxins, called beta-amyloids, are associated with an increased risk of brain disorders like of Alzheimer’s disease. Other aspects of brain function such as attention, creativity and decision-making ability are also heavily dependent on adequate sleep.

Sleep has a significant influence over our physical health as well. Not only is it essential for the growth and repair of our muscles and other cells throughout our body, it also strengthens our immune system and improves our ability to fight infection. Interestingly, sleep also helps to maintain the balance between the hormones which regulate our feelings of hunger and fullness in relation to food. Poor sleep has been shown to affect this balance which to some extent may explain why there is an increased risk of obesity with inadequate sleep over the long term.

What happens when we don’t get enough sleep?

A lack of sleep can affect our ability to make decisions, solve problems and our general mood and ability to control our emotions. Sleep deprivation has a significant effect on our cognitive functions and performance. A recent survey of Australians showed that sleepiness and sleep problems were a major source of risk on our roads with 20% of people reporting they “nodded off” while driving at some point.

Perhaps less reported is the negative affects shortened sleep time has on our metabolic health and our ability to manage our blood glucose levels. Sleeping less than six to seven hours per night has been shown to increase our risk of obesity, type 2 diabetes and heart disease.

How does sleep loss affect diabetes?

Ongoing sleep loss has been shown to lead to glucose intolerance (difficulty breaking down glucose) and insulin resistance (insulin not working effectively) – both of which lead to an increase in blood glucose levels. This effect on the balance of blood glucose levels (glycaemic control) can almost double someone’s risk of developing type 2 diabetes, as well as make it increasingly difficult to manage the condition for people living with diabetes.

Research has also shown that being sleep-deprived can increase our appetite and lead us to crave comfort foods rich in fat and carbohydrates. It is estimated that being sleep deprived can increase our total daily energy intake by approximately 20%. Additionally, the fatigue and tiredness that comes with not getting enough sleep means we are less inclined to exercise. It can be easy to see why not getting enough sleep over the long term will increase someone’s risk of gaining weight, which in turn makes it even more difficult to control blood glucose levels.

How much sleep is enough?

Your body’s need for sleep will vary on an individual basis. Factors such as age and your genetics can have a large influence. Seven to eight hours sleep is generally considered normal in the adult population. You can usually tell if you are sleeping enough by how well you function during the day. Interestingly, over-sleeping can have a similar impact on our health to under-sleeping. Here are some age-specific sleeping guidelines.

National Sleep Foundation’s Sleep Duration Recommendations:

Age	Recommended	May be appropriate	Not recommended
Newborns 0-3 months	14 to 17 hours	11 to 13 hours 18 to 19 hours	Less than 11 hours More than 19 hours
Infants 4-11 months	12 to 15 hours	10 to 11 hours 16 to 18 hours	Less than 10 hours More than 18 hours
Toddlers 1-2 years	11 to 14 hours	9 to 10 hours 15 to 16 hours	Less than 9 hours More than 16 hours
Preschoolers 3-5 years	10 to 13 hours	8 to 9 hours 14 hours	Less than 8 hours More than 14 hours
School-aged children 6-13 years	9 to 11 hours	7 to 8 hours 12 hours	Less than 7 hours More than 12 hours
Teenagers 14-17 years	8 to 10 hours	7 hours 11 hours	Less than 7 hours More than 11 hours
Young adults 18-25 years	7 to 9 hours	6 hours 10 to 11 hours	Less than 6 hours More than 11 hours
Adults 26-64 years	7 to 9 hours	6 hours 10 hours	Less than 6 hours More than 10 hours
Older adults ≥ 65 years	7 to 8 hours	5 to 6 hours 9 hours	Less than 5 hours More than 9 hours

*The above sleep duration recommendations are based on a report of an expert panel convened by the US based National Sleep Foundation and published in 2015

What is sleep apnoea and its link with diabetes?

Sleep apnoea is a common sleep condition where a person’s throat becomes partially or completely blocked while they are asleep, causing them to stop breathing. As a result, blood oxygen levels fall. Typically, people stop breathing from a few seconds up to ninety seconds. The person wakes briefly and begins breathing again. This can happen many times in a night and is known as apnoea. The person is often unaware this occurs but generally feels tired.

Symptoms and causes

Adults and children can both experience sleep apnoea. The symptoms of sleep apnoea include:

• Pausing in breathing while sleeping
• Tossing and turning
• Snoring
• Waking up and choking or gasping for air
• Feeling tired and unrefreshed after sleeping

There is a strong link between sleep apnoea and type 2 diabetes. When people are diagnosed with diabetes, it is thought that between 50-80% also experience sleep apnoea. A small research study also found 40% of adults living with type 1 diabetes had sleep apnoea.

Adults

Adults who are middle-aged or older and who are above the recommended healthy weight range are more likely to be affected by sleep apnoea. Carrying excess weight can cause narrowing of the throat due to fatty tissue. A larger waistline can also make the area around the lungs smaller, causing the throat to collapse. People may also be born with a narrower facial structure and throat which can be the cause of sleep apnoea.

Children

In children, sleep apnoea is generally caused by enlarged tonsils or adenoids. However, children with type 1 diabetes are more likely to experience sleep apnoea compared to children who do not have type 1 diabetes. In addition, sleep apnoea episodes tend to be higher in children with HbA1c results higher than 8.0%.

Treatment options

• Mild sleep apnoea is often relieved or reduced by changing sleep positions. Sleeping on your side reduces the likelihood of sleep apnoea. Special pillows or wedges can also help
• Achieving or maintaining a healthy weight and waist circumference
• Reducing alcohol consumption if you drink
• Good sleeping habits and routine prior to bed can help improve sleep.

Moderate to severe sleep apnoea requires active treatment. This may require devices such as a continuous positive airway pressure (CPAP) machine or an oral appliance such as a mouth guard that is fitted by a specialist dentist.

If you think you or someone you know may be experiencing sleep apnoea, it is recommended to see a general practitioner for a referral for a sleep study. In the case of children, a request should be made to a paediatric sleep specialist.

How do I improve my sleep?

There are some easy steps we can take prior to bedtime to help us get a full night’s sleep:

• Ensure your bedroom is dark, quiet and at a suitable temperature. This includes turning off all electronic devices such as TVs, mobiles phones and computers at least one hour before bedtime.
• Avoid large meals, caffeine and alcohol before bed
• Try to be consistent with the time you go to bed and wake up.

Regular exercise or physical activity is another effective way of improving your sleep, while also helping reduce blood glucose levels. Research has shown that these benefits can be experienced straight away with exercise having an acute positive impact on sleep. These benefits are even greater when we exercise on a regular basis and have been shown to reduce the amount of time it takes up to get to sleep (sleep latency), as well as increase the duration and quality of our sleep. Aiming for 30 minutes of some form of physical activity per day is a great place to start to experience these benefits.