Just a Thought
What this series is about ... As we age, keeping physically active is essential. It not only improves the appearance of the body, it also prevents the occurrence of health complications in the future. Join the discussion in this series as we research the various programs that can help maintain a healthy body.
Part 3: Staying Young: Sleep
Wake up Australia: The value of healthy sleep
Report by Access Economics
Sleep disorders are a large and under recognised problem in Australia.
An estimate of over 1.2 million Australians (6% of the population) experienced sleep disorders at a cost of $10.3 billion in 2004. The most common disorder is Obstructive Sleep Apnoea (OSA), affecting an estimated 4% of the population, although there are over 70 other different diagnosable sleep disorders.
Insomnias are also highly prevalent, with substantial morbidity and mortality. According to Access Economics these disorders contribute to a range of other health and social problems, with substantial health and economic impacts – accidents and injuries, other chronic illnesses, production and consumption losses, and second generation effects, particularly from childhood sleep disorders. The report quantifies some of the many impacts of sleep disorders:
Sleep disorders underlie:
• 9.1% of work-related injuries;
• 8.3% of depression
• 7.6% of non work-related motor vehicle accidents (MVAs);
• 2.9% of diabetes;
• 0.9% of nephritis and nephrosis (kidney diseases); and
• 0.6% of cardiovascular disease.
The health costs of sleep disorders themselves were $200 million in 2004, of which OSA and other apnoeas are an estimated 39%. Other major components of hospital inpatient costs ($61m) are circadian rhythm disorders, sleep-related epilepsy, non-organic sleep-wake disorders, alcohol-dependent sleep disorders, sleep-related asthma, insomnias (disorders of initiating and maintaining sleep), hypnotic and stimulant dependent sleep disorders, and other specified extra-pyramidal and movement disorders (Periodic Limb Movement Disorder and Restless Legs Syndrome).
The fact that the health costs of sleep disorders are only 2% of the $10.3 billion, the total cost of these disorders to the community suggests that perhaps too little is spent in prevention and treatment that could avoid the huge “tail” of the other indirect cost impacts across society. The health costs of other health problems caused by sleep disorders are $429 million.
The total financial costs of sleep disorders ($6.2bn) represent 0.8% of GDP, $310 per Australian, and $5,175 per person with a sleep disorder in 2004. Sleep disorders impose substantial morbidity and premature mortality on the population.
In addition, sleep disorders cost nearly 40,000 years of health life each year, as measured by DALYs (disability adjusted life years).
The report Wake up Australia: The value of healthy sleep recommends priority interventions to address the current fragmented and under-resourced sleep health landscape including:
Education and awareness-raising – for community, health professionals and public policy makers, regarding the importance of good sleep hygiene and how to achieve better sleep outcomes.
Research and development – for cause, care and cure, at the basic, applied, development and delivery levels.
Cost-effective prevention, treatment and management options – identification and funding for cost-effective interventions, such as those outlined above; and
A national coordination point – the establishment of a catalysing National Sleep Health organisation with a forward national action plan.
What does sleep do for us?
A number of tasks vital to health and quality of life are linked to sleep, and these tasks are impaired when we are sleep deprived.
Learning, Memory, and Mood
Students who have trouble grasping new information or learning new skills are often advised to "sleep on it”. That advice seems well founded.
Recent studies reveal that people can learn a task better if they are well rested. They also can remember better what they learned if they get a good night's sleep after learning the task than if they are sleep deprived.
Similarly, volunteers needed to sleep at least 6 hours to show improvement in learning, and the amount of improvement was directly tied to how much time they slept. In other words, volunteers who slept 8 hours outperformed those who slept only 6 or 7 hours.
Other studies suggest that all the benefits of training for mentally challenging tasks are maximised after a good night's sleep, rather than immediately following the training or after sleeping for a short period overnight.
Many well-known artists and scientists claim to have had creative insights while they slept. Mary Shelley, for example, said the idea for her novel Frankenstein came to her in a dream. Although it has not been shown that dreaming is the driving force behind innovation, one study suggests that sleep is needed for creative problem solving. In that study, volunteers were asked to perform a memory task and then were tested 8 hours later. Those who were allowed to sleep for 8 hours immediately after receiving the task and before being tested were much more likely to find a creative way of simplifying the task and improving their performance compared to those who were awake the entire 8 hours before being tested.
Exactly what happens during sleep to improve our learning, memory, and insight is not known. Experts suspect, however, that while people sleep, they form or reinforce the pathways of brain cells needed to perform these tasks. This process may explain why sleep is needed for proper brain development in infants.
So, not only is a good night's sleep required to form new learning and memory pathways in the brain, but sleep is also necessary for those pathways to work up to speed. Several studies show that lack of sleep causes thinking processes to slow down. Lack of sleep also makes it harder to focus and pay attention. Lack of sleep can make us more easily confused. Studies also find a lack of sleep leads to faulty decision-making and more risk taking. A lack of sleep slows down our reaction time, which is particularly significant to driving and other tasks that require quick response. When people who lack sleep are tested by using a driving simulator, they perform just as poorly as people who are under the influence of alcohol. The bottom line is: not getting a good night's sleep can be dangerous!
Even if we do not have a mentally or physically challenging day ahead of us, we should still get enough sleep to put ourselves in a good mood. Most people report being irritable, if not downright unhappy, when they lack sleep. People who chronically suffer from a lack of sleep, either because they do not spend enough time in bed or because they have an untreated sleep disorder, are at greater risk of developing depression. One group of people who usually do not get enough sleep is mothers of newborns. Some experts think depression after childbirth (postpartum blues) is caused, in part, by a lack of sleep.
Sleep gives the heart and vascular system a much-needed rest. During non-REM sleep, the heart rate and blood pressure progressively slow as we enter deeper sleep. During REM sleep, the heart rate and blood pressure have boosted spikes of activity. Overall, however, sleep reduces our heart rate and blood pressure by about 10 percent.
According to some studies, if our blood pressure does not dip during sleep, we are more likely to experience strokes, chest pain (angina) an irregular heartbeat, and heart attacks. We are also more likely to develop congestive heart failure, a condition in which fluid builds up in the body because the heart is not pumping sufficiently. Failure to experience the normal dip in blood pressure during sleep can be related to insufficient sleep time, an untreated sleep disorder, or other factors.
A lack of sleep also puts the body under stress and may trigger the release of more adrenaline, cortisol, and other stress hormones during the day. These hormones contribute to the blood pressure not dipping during sleep, thereby increasing the risk for heart disease.
Inadequate sleep may also negatively affect the heart and vascular system by increased production of certain proteins thought to play a role in heart disease. For example, some studies find that people who chronically do not get enough sleep have higher blood levels of C-reactive protein. Higher levels of this protein may suggest a greater risk of developing hardening of the arteries (atherosclerosis).
Deep sleep triggers more release of growth hormone, which fuels growth in children and boosts muscle mass and the repair of cells and tissues in children and adults. The sleep effect on the release of sex hormones also encourages puberty and fertility.
A good night's sleep on a regular basis helps people from getting sick or recovering from sickness if they do get sick. During sleep, the body creates more cytokines - cellular hormones that help the immune system fight various infections. Lack of sleep can reduce the ability to fight off common infections. Research also reveals that a lack of sleep can reduce the body's response to the flu vaccine. For example, sleep-deprived volunteers given the flu vaccine produced less than half as many flu antibodies as those who were well rested and given the same vaccine.
Although lack of exercise and other factors are important contributors, the current epidemic of diabetes and obesity appears to be related, at least in part, to chronically getting inadequate sleep. Evidence is growing that sleep is a powerful regulator of appetite, energy use, and weight control. During sleep, the body's production of the appetite suppressor leptin increases, and the appetite stimulant grehlin decreases. Studies find that the less people sleep, the more likely they are likely to be overweight or obese and prefer eating foods that are higher in calories and carbohydrates. People who report an average total sleep time of 5 hours a night are, for example, more likely to become obese compared to people who sleep 7-8 hours a night.
A number of hormones released during sleep also control the body's use of energy. A distinct rise and fall of blood sugar levels during sleep appears to be linked to sleep stage. Not getting enough sleep overall or enough of each stage of sleep disrupts this pattern. One study found that, when healthy young men slept only 4 hours a night for 6 nights in a row, their insulin and blood sugar levels mimicked those seen in people who were developing diabetes. Another study found that women who slept less than 7 hours a night were more likely to develop diabetes over time than those who slept between 7 and 8 hours a night.
Australasian Sleep Research Association
The Australasian Sleep Association is the peak scientific body in Australia and New Zealand representing clinicians, scientists and researchers in the broad area of Sleep. Its many functions include the organisation of domestic and international scientific meetings, as well as acting in an advisory capacity to government and industry.
The ASA is affiliated with the World Federation of Sleep Research and Sleep Medicine Societies, http://www.sleepaus.on.net/
Project Manager and Editor, Quality4life
28 August 2006