Updated: Jan 3
Sleep is a fascinating topic. Some people say they understand that sleep is important but then never actually do anything to prioritize it. There is always something more tempting to do than to sleep, even when your body might be telling you otherwise. On the other hand, there may be other people who say they don’t need a lot of sleep and are happy with 4 to 5 hours a night. They claim that they simply don’t feel tired and therefore no ill-effects are done. Then there are some people who would love to be able to sleep more but are unable to fall asleep or stay asleep.
So really, how important is sleep? In short, REALLY IMPORTANT! Insufficient sleep increases the risk of conditions such as: diabetes, obesity, cardiovascular disease, mood disorders, neurodegenerative disease, and more. In fact, not getting enough sleep has been associated with having a shorter lifespan. This is actually not so surprising if you understand that the sleep cycle works to regulate other biological cycles in the body and is deeply connected to metabolism, appetite regulation, the stress response, hormone regulation, and more. Sleep is also the time when the body does its repair and maintenance. This is a time for rejuvenation, growth, repair, and healing. Sleep is also deeply connected to the immune system - if you don’t get enough sleep, you are more likely to get sick from an infection or it may even contribute/exacerbate autoimmune diseases.
The Sleep Cycle
In order to dive a little deeper into the importance of sleep, we first need to understand what the sleep cycle is and how it works. There are different stages of sleep within a sleep cycle. Stages 1 and 2 are your light sleep, stage 3 is your deep sleep (sometimes this is broken down into stage 3 and 4), and then you have your Rapid Eye Movement (REM) sleep. Each of these stages have their function and purpose. Stage 1 is the transition from your awaken state to drifting in and out of drowsiness, preparing your body for sleep. Stage 2 is where light sleeping occurs and we actually spend about 50% of our time in this stage - brain waves slow and prepares the body for deep sleep. Stage 3 is your deep sleep and this is where the most rejuvenation, restoration, healing, and growth occurs in the body. Lastly, REM sleep is where you have your most vivid dreams. Here, you actually experience what’s called sleep paralysis - your brain wave activity is active and similar to that of when you are awake, whereas your body is unable to move or speak. It has been suggested that this phenomenon occurs to protect us from hurting ourselves in acting out/reacting to our dreams. It has been proposed that REM sleep helps us to form new memories, stimulate the nervous system, restore the brain chemistry to a normal balance, revitalize the brain, support sharp, alert daytime functioning, and process emotional information. As you see, the different stages of sleep are important in restoring and rebalancing different bodily functions. These 4 stages make up the sleep cycle and our body cycles through this 4 to 5 times per night.
So why did I just explain all of that? Well, because it turns out that just getting a certain number of hours of sleep per night is not the end of the story. The quality of sleep also matters. In fact, the time of the night when you turn in influences the amount of time you spend in deep sleep vs REM sleep. We spend more time in deep sleep in the first part of the night (11pm to 3am) and we spend more time in REM sleep in the second part of the night (3am to 7am). So, if you are a night owl and goes to bed well after midnight, you will spend significantly less time in the restorative/healing phase of sleep, even if you manage to get in eight hours or more of slumber. Therefore, it is important that you adjust to an earlier bedtime, preferably before 11pm (to ensure that you are asleep by 11pm), especially if you are working through a chronic health issue. This maximizes the time your body spends in the restorative/healing phase.
But that’s not all. If you want to know more about how sleep can affect your brain, immune system, and your mood, read on!
Sleep and brain health
Sleep can literally change your brain! Studies have shown that a decrease in deep sleep is linked to a change in the physical structure of the brain. The volume of grey matter in the prefrontal cortex shrinks in relation to a lack of deep sleep (stage 3 of the sleep cycle). The prefrontal cortex of the brain is the area that is responsible for executive functioning such as planning complex behaviour, personality, decision making, moderating social behaviour, as well as working with the hippocampus of the brain in the encoding and retention of memory.
As brain structure is altered, it is only reasonable to assume that brain function is also affected by a lack of sleep. And indeed, it is. For example, sleep disorders can disrupt the homeostatic drive, which helps to regulate our drive for sleep (that the longer you go without sleep, the stronger the drive for deep sleep). Cognitive functioning also declines with sleep deprivation, this includes learning difficulties, decreased attention, reduced motor control, lack of motivation, memory deficits, and so on. It has also been shown that the link between insufficient sleep and brain structure and function is bi-directional. For instance, changes in cerebral blood flow have been shown to affect sleep quantity and quality.
Sleep is so essential to brain health such that it is being considered to be used as a risk factor for neurodegenerative diseases such as Alzheimer’s Disease. For example, it has been shown in mice studies that the protein, beta-amyloid (which is characteristic of Alzheimer’s Disease), is increased during waking hours and these proteins are cleared during the period of deep sleep. When deep sleep is lacking, the clearance of these proteins is less effective, and the accumulation of these proteins can contribute to neurodegenerative diseases. In humans who experience more fragmented sleep (independent of sleep disorders such as insomnia and sleep apnea, which also increases dementia risk) go on to develop a more rapid rate of cognitive decline and is at a higher risk of developing Alzheimer’s Disease over an ensuing 6-year period. As you can see, good quality sleep is crucial in maintaining a healthy brain.
Sleep and immunity
Did you know that sleep is deeply connected to the immune system? Our immune system is our defense mechanism against foreign invaders that find their way into our bodies. When our immune system is healthy, it is efficient and diligent in seeking out pathogens and destroying them before they can cause serious harm in our bodies. Interestingly, our immune system is on higher alert when we are in deep sleep.
One way to measure the activity of the immune system is by looking at inflammatory markers and proinflammatory cytokines. These are molecules that are produced by certain immune cells (and sometimes other neighbouring cells) to alert the body that a pathogen has invaded and to signal the immune system to attack the foreign invader. Inflammation is part of the normal process of switching on the immune system.
Usually, we see a higher level of immune activity during the deep sleep stage. When the sleep cycle is disrupted (e.g. sleep deprivation/fragmentation etc), the quality of the immune response is altered. It has been shown that certain markers of inflammation (i.e. C-reactive protein (CRP), Tumour Necrosis Factor (TNF), Interleukin-6 (IL-6)) are increased during sleep deprivation. In other words, sleep loss may induce/contribute to inflammation in the body. Interestingly, this inflammatory activity is markedly more apparent in women than in men. Meaning, women appear to be more affected by sleep loss than men. Furthermore, this increase in inflammatory signalling in relation to sleep loss is associated with age, such that this phenomenon is observed more so in the younger adult population than older adults (over 55 years old). It has been postulated that sleep loss in the younger adult population increases their risks of inflammatory disorders whereas the older adult population may be more at risk of infectious disease due to blunted response to inflammatory stimulation.
So, what is the importance of these inflammatory cytokines? Well, it has been shown that even small increases in the circulating levels of proinflammatory markers have been associated with type II diabetes and cardiovascular disease. Not to mention that increases in the levels of inflammatory cytokines may induce inflammation throughout the whole body and cause metabolic changes, which could lead to a host of other chronic diseases.
Another intriguing correlation is that the inflammatory effects of sleep loss is connected to social ties. For example, one study showed that the increase in the inflammatory cytokine, IL-6, was only seen in women experiencing sleep loss who were also experiencing poor social relationships. Similarly, another study showed that poor sleep in pre-hypertensive and hypertensive individuals demonstrated increases in IL-6 and CRP only in those individuals who also reported to have low social support. This is a great example of how our bodies are interconnected on so many levels, and that physical health is not separate from mental, emotional, and spiritual health. Instead, they all work together and influence each other in maintaining the well-being of an individual.
Furthermore, this increased inflammation as a result of sleep deprivation may contribute to biological aging. Elevated inflammation is associated with the usual process of aging, sometimes termed “inflammaging”. It is believed that normal aging is a result of the accumulation of cellular and DNA damage, inflammation, and telomere shortening. Telomeres are repetition of DNA that cap the ends of chromosomes (structures in the nucleus of most living cells carrying our genetic information in the form of genes). Telomeres shorten over time and is an indication of cellular aging in humans. When there is an accelerated rate of telomere shortening it is predictive of greater disease progression and mortality. Interestingly, it has been shown that sleep disturbance (in the form of insomnia) has been correlated with shorter telomere lengths detected in the peripheral blood mononuclear cells (PBMC), suggesting that poor sleep may speed up the aging process at the cellular level and that this is most profound in the older adult population (over 60 years of age).
Sleep on emotions and mood
As mentioned before, sleep plays such an important role in the health of the brain. So, perhaps it is not so surprising that sleep also plays a prominent role in our mood and emotions. In fact, it has been shown that sleep disorders are associated with a number of psychological problems like internalizing disorders, suicidal thoughts, anhedonia, mood problems and depression. Even though psychological issues may create sleep problems, it has also been shown that sleep disorders can contribute to psychological symptoms. For instance, sleep deprivation experienced for a week or longer has been linked to poor emotion regulation and acute sleep deprivation has been shown to increase negative emotions in healthy individuals. In certain people with chronic health conditions, poor sleep can hinder healing.
Poor sleep quality has also been used as a strong predictor of depression risk. Inflammation plays an important role in depression. In fact, people who suffer from inflammatory disorders have a high comorbidity with depression. Also, markers of inflammation exist in higher levels in depressed compared to non-depressed individuals, such that inflammatory markers like IL-6 and CRP may be used as predictors of depression occurrence. What’s more, acute increase in inflammation has been shown to increase depressive moods, whereas the suppression of endogenous inflammation seems to diminish depressive symptoms in depressed patients who express a high level of inflammation. Interestingly, in response to poor sleep, women appear to be more affected in the worsening of depressive symptoms as opposed to men. Since inflammation initiates the progression of depression, perhaps, women produce more inflammatory molecules and/or are more sensitive to the inflammatory cytokines produced as a result of poor sleep.
Okay, so sleep is important…. But how can we sleep better?
By now, I hope it’s clear that you understand just how essential sleep is to your health and well-being. So what can you do to improve your sleep hygiene? Here are some suggestions to help you get started:
Be consistent with your bedtime and wake time, this helps your body set your internal clock and find balance in your circadian rhythm. If you get enough sleep, you should be able to wake up without an alarm. Otherwise, it usually means that you need an earlier bedtime.
Avoid sleeping in on the weekends - the more your weekday and weekend schedules differ the more the effect of jet lag-like symptoms. Instead, take a nap if needed rather than disrupting your daily sleep/wake routine
Napping might be a good way to catch up on on lost sleep, but if you take regular naps and you have trouble falling asleep at night, then you might need to cut down on the daytime naps, or limit naps to 15 to 20 mins, and do this in the early afternoon instead of close to the evening
Avoid caffeine - they can affect some people 10 to 12 hours after its intake.
Expose yourself to sunlight in the morning - as close as you can to waking the better. Then spend more time out in the sun during the day - if possible, do your exercise or have your lunch break outside.
Use as much natural light in your living/working space as possible
Exercise - it helps you to feel less sleepy in the day and have more restful sleep at night. It also increases the period of time you spend in deep, restorative sleep. It may take a few months of regular exercise to see the full benefit - so be patient. However, if exercising close to bedtime, avoid stimulating, vigorous exercises - instead, go for more meditative practices like Yoga or gentle stretching.
Avoid/minimize blue light exposure in the night (phones, tablets, computers, TV, etc)
Watching TV is actually the opposite to relaxing the body - blue light suppresses melatonin (sleep hormone). Also many programs are stimulating to the nervous system and doesn’t help you to settle in for sleep.
Don’t eat a big meal before bed
Avoid alcohol before bed - it disrupts your sleep cycle
Cut back on sugary food and refined carbs during the day - they trigger wakefulness in the night and pull you out of the more restorative stages of sleep
Still having difficulties?
For those of you who have a hard time falling or staying asleep, we feel you. Sleep is a complex matter. You may want to speak to your healthcare professional to find a solution for your individual concerns. In the meantime, if you do find yourself wide awake in the middle of the night, try to stay out of your head - it doesn’t help to stress about not sleeping. Instead, aim for relaxation rather than putting pressure on yourself to get back to sleep. You may try to do some meditation, body scan exercise, visualizations and so on. If you have been awake for 15 minutes or more, you may opt to do some quiet and non-stimulating activities, such as reading a book – don’t use electronic devices and keep lights low. Postpone worrying and brainstorming at this time. Write down notes to organize your thoughts and to put your mind at ease if it helps you to stop worrying but then put your to-do list away with the intention to deal with it the next day. Lastly, you may want to consider a change to your current diet and lifestyle.
Contact me to learn more about how I can help you with your sleep concerns.
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