The Many Benefits of Sleep – The Body
Early to bed, early to rise,
Makes a man healthy, wealthy and wise.
If you’ve been following along with our Health Matters blog series on sleep you’ll have learned a great deal about the subject so far! Today, however, I want to touch on what I believe is the most interesting aspect of sleep – sleep’s incredible health benefits. However, before we can appreciate the amazing things that take place when we sleep, we need to consider some of the very negative consequences of not getting enough sleep. We will then have a much greater appreciation of sleep’s role in maintaining both the health of our body and our brain. Keeping the following health benefits uppermost in your mind may serve as the best motivational tool you’ll need to develop a consistent sleep routine.
Most people understand the important role that nutrition and exercise play in the maintenance of optimal health. However, few realize that getting adequate nightly sleep could be more important than either nutrition or exercise. Consider this for example: while it may take many years to notice the effects of lack of physical activity on the body, and it is possible to survive many days without any nutrition, sleep deficit has immediate detrimental impacts on the body and can be deadly. So therefore, sleep is certainly up there with these important health practices.
Apart from the very rare outliers amongst us, we should all be aiming for 8 hours of sleep every night. This number is based on a growing body of research.
The Centers for Disease Control and Prevention reported in Sleep and Sleep Disorders – Data and Statistics, 2017 that less than 7 hours per night resulted in a clear increase in heart disease and strokes, asthma, chronic obstructive pulmonary disease, cancer, arthritis, depression, chronic kidney disease, and diabetes.
Professor H. Craig Heller of Stanford University in his book, Secrets of Sleep Science: From Dreams to Disorders, says this about sleep: “Sleep is just as essential to life as nutrition and exercise. In fact, lack of sleep impairs performance, exacerbates psychological and psychiatric problems, and contributes to a host of illnesses. And the consequences of too little sleep extend beyond the merely personal. From automobile accidents to lost productivity at work to major disasters, such as the Exxon Valdez oil spill, sleep deficits have levied a heavy toll on society as a whole”. Professor Heller points out that sleep impacts many facets of our life. It influences our moods, cognitive abilities, energy levels and the function of our organs.
In this blog, we will consider the impacts of sleep deprivation on the body, and by contrast the benefits to the body of consistent, quality sleep. In the next blog, we’ll focus on the impacts of sleep on mental function.
Sleep and our Immune System
Immune health and sleep health go hand in hand: reduced sleep can impair immune function, while adequate sleep of around 8-hours can improve it. If our immune system was compared to an armory for waging war against infection, sleep would be likened to the administrator responsible for replenishing the armory, as well as for keeping each weapon in tip top condition and ready for use each day.
Many sleep experiments have been conducted, both on human and animal subjects, to study both the effects of sleep deprivation and optimal sleep of eight hours on the immune system.
For instance, rats deprived of all sleep stages survived only three weeks instead of their usual two to three years, and sleep deprived rats developed sores and reduced body temperatures, indicating impairment of their immune systems.
In humans, an experiment done on healthy males showed that even one night of partial sleep deprivation led to a 70% reduction in natural killer cells and to a diminished cellular immune response in the volunteers. A subsequent night of recovered sleep restored natural killer cell levels to baseline levels, but left cellular immune response suppressed, showing that sleep plays a significant role in regulating and modifying our immune function. With levels of sleep deprivation skyrocketing in our industrialised world this level of immune deficiency is alarming, and may be contributing to the risk of many cancers.
During sleep our immune system produces special proteins called cytokines that aid in the fight against infection and sickness. Feeling tired and sleeping more when we are sick is our body’s response to creating the conditions necessary to manufacture the cytokines needed in the healing process.
Other experiments have shown a link between developing colds and sleeping less than 7 hours per night, again showing the immense importance of sleep in the modulation of immunity.
Even our DNA genetic code suffers with lack of sleep. In an experiment to investigate the effect of sleep on our genes, a group of healthy adults had their sleep curtailed from 8 to 6 hours each night for a week after which their gene activity was measured and compared relative to when they were getting a full night’s sleep. The results were dramatic. Lack of sleep altered the function of 711 genes in two ways: half the genes increased in activity, while the activity of the other half was downregulated. Those genes which showed a decrease in activity were those necessary for maintaining a healthy immune system, and so lack of sleep again was coupled to immune deficiency. The genes that were more active were linked to the development of tumours, or associated with chronic inflammation, or were genes allied to stress.
The less sleep we get, the shorter our lives will be. Getting 8 hours of sleep is crucial for the maintenance of optimal immune function, for combatting illness and infection and essential for living a long, healthy life.
Sleep and the Cardiovascular System
Our heart rate and breathing change as we journey through the five stages of sleep, first slowing down from stage one to four and then picking up again in stage 5 REM sleep. These changes boost cardiovascular health.
While we sleep hormones that maintain heart health and that keep blood vessels in good condition are released. If we do not get the required amount of sleep the release of these hormones is disrupted, leading to the exacerbation of existing blood pressure problems, deterioration of the heart, putting people at far higher risk of cardiovascular diseases: heart disease, high blood pressure, and stroke.
In a TED Talk, Sleep is Your Superpower, which has been viewed by over 6 million people on YouTube, Matt Walker, Professor of neuroscience and psychology at Berkley, California and Director of the Centre for Human Sleep Science had this to say about sleep, “I could tell you about sleep loss and your cardiovascular system, and that all it takes is one hour. Because there is a global experiment performed on 1.6 billion people across 70 countries twice a year, and it’s called Daylight Savings Time. Now in the Spring when we lose one hour of sleep, we see a subsequent 24 % increase in heart attacks that following day. In the Autumn, when we gain an hour of sleep, we see a 21% reduction in heart attacks. Isn’t that incredible. And you see exactly the same profile for car crashes, road traffic accidents and even suicide rates.”
Sleep is crucial to maintain cardiovascular health and prevent diseases of the cardiovascular system.
Sleep, Rejuvenation and Growth
During deep sleep some pretty amazing things happen to the body in terms of its rejuvenation. The impact of daily stresses, exposure to UV radiation, and other toxins are damaging to our bodies. Deep sleep is an opportunity for our bodies to repair and heal the damage done to body tissues, for it is during deep sleep that the manufacture of the building blocks of life, proteins, is increased, while their breakdown is decreased. For children and young adults, it is during deep sleep that growth hormone is released.
Deep sleep has been described as the “beauty parlor” of the body because of its powerful rejuvenating effect and the healing and repair that take place during this time.
Sleep’s Role in the Battle Against Weight Gain.
Lack of quality sleep is strongly associated with weight gain and obesity. This association is due to several factors.
First of all, sleep regulates the two appetite hormones leptin and ghrelin. Leptin is the hormone that suppresses our appetite. You could say that leptin is “the good guy” as it sends signals to our brain to indicate that we are satiated. Ghrelin works in the opposite direction to increase our appetite, so could be viewed as “the enemy”. It lets us know that we are hungry or require more food to be satiated. Unfortunately, lack of sleep disrupts these two appetite hormones, so that the “good” hormone, leptin is suppressed, while levels of ghrelin, “the enemy”, increase with a corresponding increase in our appetite. As a consequence, for many people who sleep fewer hours per night, the result is an increased consumption of between 200-400 calories per day, with an inevitable gain in weight.
Secondly, when we are tired, the kinds of food that we desire shifts. We prefer more refined and highly palatable foods like cake to complex, less appetising carbohydrates like leafy greens. This has been borne out by researchers in an experiment that compared the brains of two groups of volunteers; a sleep deprived group that was kept awake all night and a control group that was allowed a full night’s sleep. The next day the volunteers were placed inside an MRI scanner and shown pictures of food, ranging from highly desirable foods, such as chocolate to less desirable foods, such as broccoli. It was found that the pleasure centres in the brains of sleep deficient individuals lit up in response to the pictures of more desirable food, but that the areas of the brain responsible for moderating and tempering or constraining our emotions and impulses were disabled by sleep loss.
It isn’t surprising then, that being tired leads to an increased appetite, a desire for highly palatable foods, and a decreased resistance to temptation. The result – poor control and weight gain.
Thirdly, those of us who under-sleep tend to be less motivated to exercise.
Poor sleep is one of the biggest risk factors for weight gain in both adults and children. Good sleep positively regulates the two essential appetite controlling hormones, leptin and ghrelin, so that we eat fewer calories. Good sleep reduces our desire to eat more palatable, sugary foods, increases our will power and provides us with more motivation to exercise.
In short, it is essential to get daily, adequate sleep to maintain or lose weight
Sleep and Athletic Function
Many studies have shown that prolonged sleep improves athletic performance in whatever field the athlete practices. For example, a Stanford study showed that male basketball players ran faster and improved their shooting, and also reported increased physical and mental wellbeing. However, there are times when athletes experience periods of sleep deprivation before major events, due to jet lag and the rigors of the competition itself. It is interesting to note that negative effects on an athlete’s physical performance caused by this short-term sleep deprivation have not been found to be conclusive, although time to exhaustion was quicker. On the other hand, loss of sleep in these situations is well known to reduce mental performance.
The restorative effects of regular, quality sleep are important for an athlete’s physical recovery, long term performance and mental state by refreshing and energizing them, giving them the motivation needed to face another day of hard training and to engage in competitive events.
As we have already seen it is during sleep that the repair of cells and tissue occurs. Studies have linked increased risk of injuries in middle and high school sports performers with long term sleep deprivation.
In addition, immune function is enhanced by sleep, as cytokine hormones, produced during sleep are required to fight infections, like the common flu, and to avoid the risk of immunosuppression.
Athletes rely on a positive outlook to be at the top of their game. Lack of sleep is known to increase mental health problems like depression and anxiety, which can translate into a defeatist mindset. It also contributes to negative thoughts, feeling cranky, brain fog and therefore decreased reaction times, decreased accuracy, reduced clarity in thinking and faulty decision making.
Sleep deprivation has also been linked to poor learning outcomes. While this is relevant for us all, and will be discussed in our next blog in more detail, it impacts athletes when they are learning new skills, tactics or when trying to improve a technique.
Athletes and non-athletes alike need good quality, regular sleep to maintain their physical performance and especially their mental state. Sleep provides the much-needed motivation to exercise, adopt the right mental focus and concentration, give the body the opportunity to be recharged. Sleep also enhances the repair of damaged tissues and allows the immune system to be restocked with immune factors.
We all want that extra stamina and vitality each day to be successful and effective at work, empower and contribute to the needs of our families at home and creatively enjoy both relaxing and active leisure time. Well, sleep is one of the important keys to achieving all these things. It is clear that our physical health is negatively impacted by sleep deprivation while daily, quality sleep of 8 hours reaps massive rewards in terms of our physical wellbeing. I hope that this blog will act as a catalyst to making a positive change in your life for the better and that you will take time out to sleep!