Sleep - Part 1: WHY we need sleep!
Many people aren't aware just how important sleep is for our health. It underpins all of our health efforts, and is the foundation of human health. So let’s cover an overview of why we sleep, including looking at sleep stages, how they benefit us in different ways, and the key issues that can arise when we're not getting enough sleep.
More than just avoiding the yawns…
It’s important to understand the reasons why the body needs more sleep, and that having a good night's sleep is so much more important than just the avoidance of feeling tired the next day. Obviously, there's a reason that we all sleep. Some of us might consider it to be a bit of a nuisance and something that interrupts your daily life. Everyone can get really busy and if we could have a couple of extra hours in the day to get things done, what's the point of spending all of our precious time just lying down with our eyes closed?
If you think about sleep from an evolutionary perspective, it makes no sense that over thousands of years we'd spend a third of our lives doing something that doesn't have a vital role to play, not only for our individual health but for the species as well. Unfortunately if you try and cheat sleep along the way or cut it out, it's probably going to catch up to you in some way or another in the short term or long term.
Sleep is the foundation of good health!
People often think of lifestyle factors such as diet, exercise and sleep as the three pillars of health. A more efficient way to think about it is your diet and your exercise on a foundation of good sleep. If you're not getting good quality sleep then it's going to undo all the hard work that you might be putting in other areas of your life. When we are well rested and have had a good night's sleep, it underpins all of our good health efforts. Exercise is going to be more effective, nutrition is going to be more effective, meditation is going to be more effective, you're going to be better able to learn new skills and create better memories, become more emotionally resilient, your immune systems will function better, your brain health will improve and you will reduce your risk of cognitive decline (just to name a few benefits)!
Quick fact! It’s also been found that beauty sleep may be a proven concept! While we're more rested, apparently we're considered more attractive by other people!
We know that when we are sleep deprived, which many of us are at different stages of our lives, our bodies and our brains just struggle to function effectively and optimally. We know that when we're not getting enough rest, we fail to fully heal, it's harder to lose weight and if you do lose any weight it's more likely that it's going to be the loss of muscle mass rather than the loss of fat tissue, which we obviously want to avoid. We know that when we're not rested enough, our bodies are in a constant state of distress that predisposes to a range of chronic health conditions - weight gain, diabetes, heart disease, cancer, mental illness, and even dementia and cognitive concerns as well. Some experts believe that we should be seeing waking hours as low level brain damage, and that when we sleep it's neurological sanitation for the brain.
R.E.M. (the sleep stage, not the band!)
Sleep is not just simply a loss of consciousness. It's a highly active brain state that's fundamental to our health.
There are two different kinds of sleep that are characterised by the types of brain waves that are occurring. The shallow, rapid wave sleep is called rapid eye movement (REM) sleep. It’s characterised by small flickering or fluttering of your eyes underneath your eyelids as you're sleeping, and is typically a more active stage of sleep. Deeper sleep is called non-rapid eye movement (non-REM). There's much slower brain waves happening at this point. Across the course of the night we cycle through these different stages of sleep beginning with deeper sleep earlier in the night and then transitioning to lighter/REM sleep later in the night. Both of these are equally as important; missing out on one can be detrimental. If we look at a full sleep cycle of non-REM sleep and REM sleep, it lasts about 90 minutes. We have multiple cycles every time we sleep.
These different sleep stages have different purposes. Non-REM sleep is when the body and brain relaxes fully, which helps to reduce stress and improves your heart health. In this stage, a variety of hormones are released which promote tissue growth and repair which restores our body. Non-REM sleep is really crucial to remembering learned facts and retention of individual memories. Alternatively, REM sleep is when we dream. When we dream, it helps us to creatively organise all the information that we've taken in during the day. Dreams themselves appear to take the painful sting out of difficult or even traumatic episodes that we've experienced during the day. In this way, dreaming provides “emotional first aid”, so that when we wake up the next morning we've had a bit of a psychological resolution to any sort of traumatic things that may have occurred the day before. Dreams also help us connect new information to our existing knowledge, and in this way it helps us with creativity and problem solving. REM sleep phase is also really important for learning and getting better motor skills. For example, trying to upskill with guitar. When learning a new tune and there comes a part where it becomes a challenge, during the REM stage of sleep the brain is practicing that part of the song over and over again. You're more likely to wake up the next morning and play it with more ease. A similar example is when you're doing a puzzle or crossword, and you get to that point where you're stuck for a solution. Oftentimes you can sleep on a problem and the next day it appears a lot simpler than what it was.
The Effects of Lack of Zzzz’s
Let's delve into what happens when we don't get enough sleep, which is unfortunately a big population of Australia and around the world. Most of our knowledge about this comes from studies that look at a lack of sleep and what impact that can have.
Weight Management
A lack of sleep can be associated with weight gain or less successful attempts at weight loss. There's a hormone called ghrelin, which is a hunger hormone, and if that's being produced you're probably more likely to be hungry. There's another one called leptin, which is the satiety or fullness hormone. If that's being produced, you're less likely to feel hungry. With poor sleep, the amount of ghrelin gets overproduced and leptin gets under produced, meaning there’s a higher chance you’re going to be more hungry more often the next day.
Additionally, lack of sleep can mean we make poorer choices when it comes to food. There was an interesting study that was done around sleep deprivation and food choice. Essentially participants were in a hotel and offered a buffet full of both healthy food and less healthy food. People that were more sleep deprived chose the unhealthier options, regardless of their body composition or attitudes toward food. People who were more rested were more likely to go for the healthier options.
If we're getting less quality sleep it is more difficult to lose fat stores, which is obviously what we're wanting to do when we're trying to lose weight. Additionally, it’s easier to lose lean muscle mass when not sleeping as much as we could be, even when we're on a diet. A lack of sleep or poor night's sleep can lead to more insulin resistance. Insulin is the hormone that has a major role in managing blood sugar levels. There has been a study that showed people that slept four hours in the night compared to those who slept more than 4 hours were 40% less effective at absorbing the glucose from their blood and led to higher blood sugar levels the next day.
So if you’re finding it really hard to lose weight, feeling constantly hungry and not making good food choices, sleep might be playing a role.
Immune Function
When we are rested, our bodies are better at producing antibodies that make us resistant to infections. If we do fall unwell, our bodies are producing more cytokines to fight off the infection and we're likely to recover faster. When we're sick, our immune system actively stimulates the sleep system as well, demanding that we get more sleep. Even just one night of less sleep reduces our immune system's ability to help us.
One study has looked at sleep and its impact on resistance to the common cold. The study took a group of people and measured their sleep for a week. They were then quarantined and injected with the common cold virus. They found a linear relationship between sleep duration and the likelihood of developing symptoms of the common cold. For those getting an average of 5 hours sleep per night, they had about a 50% infection rate. For those who were getting 7 hours per night, they had an 18% risk of developing symptoms of the common cold.
There is also a study looking at the effectiveness of the flu shot as well. We know the flu shot is only effective if your body reacts to the flu shot by producing antibodies. As mentioned above, we know that sleep profoundly impacts how well the body does this. In this study, people only getting 4.5 hours of sleeper night during the week prior to getting the flu shot, they had a 50% lowered immune response to the flu shot compared to people getting 8 hours per night.
Cognitive Ability
The buildup of toxic plaques in the brain are detrimental to the neurons of your brain cells and characterise conditions such as dementia, Alzheimer's disease and forgetfulness. This is particularly seen in the frontal lobe of your brain, which is an area associated with deeper non-REM sleep. This stage of sleep is significantly disrupted in those with Alzheimer's disease. More buildup of this toxic plaque can lead to severe deep sleep loss, and therefore the ability to consolidate new memories which is a typical part of cognitive decline and dementia as well. This can clearly become a vicious cycle.
Furthermore, there are cells in your brain called glial cells (which comes from the word glue). When you're sleeping those cells shrink and allow a flow of cerebrospinal fluid to cleanse the brain of the day's metabolic buildup, which can include these toxic plaques that can lead to dementia and Alzheimer's disease.
Cardiovascular health
There is a worldwide study that everyone undertakes twice per year around heart health and sleep, and it's called daylight savings. A specific study in the U.S. recorded the changes in heart attack hospitalisations over 3 years around daylight savings time changes. They found an increase of 24% in the days following losing an hour of sleep, and a 21% decrease the days after gaining an hour’s sleep. You're not going to get more powerful evidence that good sleep is playing a role in good cardiovascular health!
Don’t drive drunk… or tired!
Sleep deprivation is a huge contributor to road accidents. We know that because being awake for long periods of time reduces our alertness. It’s been found that being awake for 19 hours and operating on 5 hours sleep results in the same level of alertness as blowing a 0.05 blood alcohol reading!
Learning and memory
There's a lot of research that looks at sleep deprivation and your ability to learn new facts and concepts. In simple terms, if you don't sleep the night after learning something, you lose the chance to consolidate it. This is particularly relevant for kids and teenagers who study late into the night and cheat sleep. They are less likely to retain those facts the next day. We know that alcohol has a similar effect as well. You're far less likely to wake up the morning after reading or watching a documentary and remember the things you learnt if you have alcohol in your system.
You should now have a better understanding of why sleep is so important and how much it affects all aspects of your health.
