What is the purpose of sleep & what happens during sleep?
There’s more to sleep health than meets the eye. Sleep is essential for good health. In fact, we need sleep to survive — just like we need food and water. So, it’s no wonder we spend about one-third of our lives sleeping.
To date, scientists have found that sleep helps the body in several ways. The most prominent theories and reasons are:
According to the energy conservation theory, we need sleep to conserve energy. Sleeping allows us to reduce our caloric needs by spending part of our time functioning at a lower metabolism. This concept is backed by the way our metabolic rate drops during sleep. Research suggests that 8 hours of sleep for human beings can produce a daily energy savings of 35 percent over complete wakefulness.
Another theory, called the restorative theory, says the body needs sleep to restore itself. The idea is that sleep allows cells to repair and regrow. This is supported by many important processes that happen during sleep, including:
- muscle repair
- protein synthesis
- tissue growth
- hormone release
The brain plasticity theory says sleep is required for brain function. Specifically, it allows your neurons, or nerve cells, to reorganize. When you sleep, your brain’s glymphatic (waste clearance) system clears out waste from the central nervous system. It removes toxic byproducts from your brain, which build up throughout the day. This allows your brain to work well when you wake up.
Research suggests that sleep contributes to memory function by converting short-term memories into long-term memories, as well as by erasing, or forgetting, unneeded information that might otherwise clutter the nervous system.
Sleep affects many aspects of brain function, including:
Areas of the brain in which sleep increases activity include:
One example of how sleep can help regulate emotion occurs in the amygdala. This part of the brain, located in the temporal lobe, is in charge of the fear response. It’s what controls your reaction when you face a perceived threat, like a stressful situation. When you get enough sleep, the amygdala can respond in a more adaptive way. But if you’re sleep-deprived, the amygdala is more likely to overreact.
Research shows that sleep and mental health are intertwined. On the one hand, sleep disturbances can contribute to the onset and progression of mental health issues, but on the other hand, mental health issues can also contribute to sleep disturbances.
Sleep affects your weight by controlling hunger hormones. These hormones include ghrelin, which increases appetite, and leptin, which increases the feeling of being full after eating. During sleep, ghrelin decreases because you’re using less energy than when you’re awake. Lack of sleep, however, elevates ghrelin and suppresses leptin. This imbalance makes you hungrier, which may increase the risk of eating more calories and gaining weight.
Recent research shows that chronic sleep deprivation, even as few as five consecutive nights of short sleep, may be associated with increased risk of:
- metabolic syndrome
- type 2 diabetes
Proper insulin function
Insulin is a hormone that helps your cells use glucose, or sugar, for energy. But in insulin resistance, your cells don’t respond properly to insulin. This can lead to high blood glucose levels and, eventually, type 2 diabetes. Sleep may protect against insulin resistance. It keeps your cells healthy so they can easily take up glucose. The brain also uses less glucose during sleep, which helps the body regulate overall blood glucose.
A healthy and strong immune system depends on sleep. Research shows that sleep deprivation can inhibit the immune response and make the body susceptible to germs. When you sleep, your body makes cytokines, which are proteins that fight infection and inflammation. It also produces certain antibodies and immune cells. Together, these molecules prevent sickness by destroying harmful germs. That’s why sleep is so important when you’re sick or stressed. During these times, the body needs even more immune cells and proteins.
While the exact causes aren’t clear, scientists think sleep supports heart health. This stems from the link between heart disease and poor sleep. Lack of sleep is associated with risk factors for heart disease, including:
- high blood pressure
- increased sympathetic nervous system activity
- increased inflammation
- elevated cortisol levels
- weight gain
- insulin resistance
Thus, the Centers for Disease Control and Prevention (CDC) says the average adult needs 7 hours of sleep a night. Getting less than that on a regular basis can lead to health problems, many of which can hurt your heart health.
Drivers of Bad Sleep
If you ever feel drowsy and exhausted when you wake up, or you constantly experience daytime sleepiness, there may be something wrong with your sleep. A good night’s sleep is key to restoring physical energy and is critical to maintaining mental health. According to Sleep Foundation, between 10% and 30% of adults in the US struggle with chronic insomnia, and for adults over age 40, 69% of men and 76% of women experience sleep disruption (i.e. going to the bathroom) at least once per night. What’s wrong? In fact, many of the factors that lead to poor sleeping quality can be controlled on the individual scale, and here are some common drivers of poor sleep.
Alcohol consumption before bed can cause people to fall into deep sleep rather quickly compared to those who did not drink alcohol. This can create an imbalance between different sleep stages, decreasing overall sleep quality. As a result, people who drink alcohol before going to bed often experience shorter sleep duration and more sleep disruptions.
There has been an increase in the popularity of caffeine content in beverages and foods, which should remind people to be wary of the amount of caffeine they consume on a daily basis. The research study results from the Journal of Clinical Sleep Medicine suggests that people should limit caffeine intake for a minimum of 6 hours before bedtime. Caffeine consumption within 6 hours prior to bedtime may result in important sleep disruptions.
Mental health conditions: stress, depression, anxiety
As the world becomes faster and faster, more people face the pressure of a fast-paced environment, leading to an unstable mental state and higher possibility of experiencing anxiety and depression. Unhealthy mental states and poor sleeping quality are mutually reinforcing. In other words, they have a bidirectional relationship, where the occurrence of one state will contribute to the occurrence of the other.
According to Young’s medical research results, nasal congestion and the resulting breathing through your mouth at night increases the risk of suffering from sleep disorders like sleep apnea, hypopnea, and snoring. These sleep-disordered breathing symptoms are likely to interrupt your sleep and cause daytime fatigue.
The last thing many people do before going to sleep is scrolling through their phone. It has become a normalized habit, but staring at a screen before bedtime can cause serious sleep insomnia. The light from electronic screens can stimulate our nerves and delay our transition to sleep, keeping the brain busy and wound up. Interactions with screens include watching TV, evening texting, and video games, etc.
Uncomfortable bedroom environment can negatively affect your sleep quality, like uncomfortable room temperature, amount of light, noise level, etc.
Life is getting busier, but there’s still time for exercising! Research from Johns Hopkins University shows that a moderate amount of exercise during daytime increases the amount of deep sleep. Exercising also helps to stabilize mood and decompress the mind. However, be careful about the time you exercise! You should avoid vigorous exercise within 4 hours prior to going to bed, because aerobic exercise may create a level of activity in the brain that keeps people awake. Also, increasing body temperature after exercising conveys a signal to the body that it is time to be awake!
Sleep Hygiene (i.e. good sleep habits) is key to achieving better sleep quality. Click here to get tips from the CDC on how to achieve better sleep.
Consequences of Bad Sleep Health
We have all felt the impacts of not getting enough sleep. We feel drowsy and challenged by getting through our day. While that is never fun, it is temporary and might even feel manageable for you. However, there is a lot of misinformation related to sleep that gets tossed around, especially in regards to its importance. It is crucial to consider the long-term or harmful consequences that come with not getting enough sleep. Whether you don’t tend to sleep for long enough, or your sleep is interrupted, you may begin to see these effects on your body.
Without sleep, the brain has no time to recover and will struggle with various types of thinking. Your ability to learn and retain new information will be reduced, as sleep and memory are closely connected. As you sleep, your brain is working to consolidate what happened to you that day. So, when you don’t give your brain a chance to catch up, your memory suffers. You are even at risk of creating false memories. You may also find yourself struggling to concentrate and complete tasks, not being able to problem solve at the level you usually can at work or in regular day-to-day activities.
Sleep problems are particularly common in patients with anxiety and depression. 75% of depressed individuals show signs of insomnia. In fact, depression and lack of sleep are thought to be mutually reinforcing. When you are able to get sufficient sleep, your brain is able to repair its ability to process emotional information. A brain that is low on sleep will have a lowered ability to process when something positive happens to you. As a result, your mental health may be negatively affected.
Lack of sleep not only affects how susceptible you are to illness, but it can also affect how quickly you are able to recover. As well as your cognitive memory, sleep strengthens immune memory. Sleep allows the immune system’s ability to remember how to recognize and react to threats to the body. Breathing and muscle activity slows down during sleep. This frees up energy for the immune system to perform critical tasks that strengthens your immune system.
Risk of Disease
Not sleeping influences the way the body processes the glucose that cells use for fuel. As a result, insufficient sleep may increase the risk of Type 2 Diabetes. Poor sleep can also result in conditions to worsen in individuals with diabetes or prediabetes.
There is also a definite link between not getting enough sleep and cardiovascular disease. If someone already has hypertension, one night of insufficient sleep can cause elevated blood pressure on the following day.
If you are someone who is concerned with maintaining or losing weight, sleep may be creating more of a challenge than you think it is. When you do not get sufficient sleep, a hormonal imbalance is triggered. This may cause you to reach for food more often than usual. Additionally, the food you reach for may also likely be higher in calories and fat. Even if you are able to fight these cravings off, your metabolism will also be negatively affected.
Risk of Accidents
If you haven’t gotten enough sleep, your risk of being involved in an accident is increased. The effects of bad sleep are even comparable to the effects of being drunk. Overly sleepy employees are 70% more likely to be involved in workplace accidents than colleagues who are not sleep-deprived. This makes sense, as people who don’t get enough sleep will be more impulsive with their decision making. It can also affect your balance and coordination.
In general, sleep is crucial for a high-quality life. Sleep deprivation can even affect your overall lifespan. Good sleep is the key to a long and happy life with the most professional and personal success.
Sleep Apnea and Sleep
Given how important sleep is for the functioning of your body, it is also important to be informed of the potential sleep disorders that affect so many Americans. One of the most common sleep disorders is sleep apnea, which happens when breathing repeatedly pauses while you sleep. You may be surprised to learn that across the US, sleep apnea is actually estimated to impact almost 30 million adults’ sleep experiences, which is around 12% of the US population! In fact, the Journal of Clinical Sleep Medicine found that the estimated cost burden of undiagnosed obstructive sleep apnea among US adults was ~$149.6 billion in 2015, with ~$86.9 billion due to lost productivity and absenteeism and ~$26.2 billion of due to motor vehicle accidents!
Types of Sleep Apnea
Sleep apnea can further be broken down into different categories: There is obstructive sleep apnea (most common), which occurs when throat muscles relax and restrict the throat airways. In contrast, central sleep apnea occurs when the brain fails to send the necessary signals to breathing muscles. Central sleep apnea is more difficult to treat and often occurs among people who are seriously ill from other causes like chronic heart failure and Parkinson’s Disease. Complex sleep apnea describes those who have both obstructive and central sleep apnea. Positional sleep apnea describes sleep apnea that occurs only in certain positions of sleep, most commonly the supine position (laying on your back). If diagnosed with sleep apnea, the doctor should provide you with a description of which type(s) of sleep apnea you are suffering from.
Before consulting the doctor, one should look for symptoms that may point to sleep apnea. Some of these symptoms may include:
- Snoring loudly
- Gasping for air during sleep
- Dry mouth when you wake up
- Difficulty staying asleep (insomnia)
- Daytime sleepiness (hypersomnia)
- Morning irritability
- Mood swings
- Sexual dysfunction
- Trouble concentrating
- Heavy night sweats
How Sleep Apnea Impacts Overall Sleep Health
Sleep apnea often results in micro-arousals/micro-awakenings, which are the couple of seconds when you wake up and change your position before going back to sleep without any memory. Repeated micro-awakenings throughout the night are caused by sleep apnea as your brain forces you to wake up in order to intake oxygen. These repeated micro awakenings prevent you from falling into a deep level of sleep throughout the night.
Severe sleep apnea can also have detrimental effects on your overall health if left unaddressed. By depriving your body of oxygen during the night, sleep apnea can worsen symptoms of asthma and chronic obstructive pulmonary disease (COPD). People with sleep apnea are also more likely to develop a resistance to insulin, develop/worsen digestive problems like liver scarring and heartburn, be at increased risk for heart attacks/strokes, and develop a decreased sex drive and/or erectile disfunction. Complex sleep apnea, in particular, can cause alarming neurological symptoms like numbness and tingling.
Extensive studies have been conducted by the American Academy of Sleep Medicine to further investigate the health consequences of sleep apnea. For example, a study in hypertension discovered that treating sleep apnea was correlated with a favorable reduction in blood pressure. Another neuroimaging study found that untreated severe sleep apnea patients have a significant reduction in white matter fiber integrity in brain areas associated with cognition, mood, and daytime sleepiness. However, this effect was found to be reversible with CPAP therapy, which will be discussed next.
Sleep Apnea Treatments
There are numerous treatments available for sleep apnea, and the appropriate course will depend on your individual medical history and diagnosis. However, most people are placed on a CPAP system, which stands for Continuous Positive Airway Pressure Machine. The CPAP system delivers humidified oxygen to your nose and mouth via a mask, which creates air pressure that keeps your throat open while you sleep. However, the CPAP system can be very uncomfortable for the first few weeks and may take some time to get used to and may take several weeks to become accustomed to. During the course of these adjustment weeks, patients will likely experience worsened sleep quality. If you find that the CPAP system is hard to become accustomed to you may want to seek alternative treatment options.
The use of an oral appliance(also known as a mandibular oral device) is the most popular alternative treatment. The oral device is a retainer-like device that pulls your jaw slightly forward, allowing for oxygen to flow more easily through your throat airways. The pros of this treatment include a much easier and quicker adjustment period and immediate improvements in sleep breathing quality.
In the case that no treatments work, surgical procedures like jaw repositioning and tissue shrinkage may be last case scenarios. These procedures are usually considered after a three-month trial of other treatment options.
There’s no time like the present moment when it comes to working on your sleep health.
Where are you in your sleep journey?