Sleep Strategies To Live Longer and Be Stronger

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Sleep is restorative for the body and essential for optimal brain function. Read on for motivation to prioritize sleep for your brain health!

Too little sleep has negative effects on brain health and cognitive function. Did you know that it can even raise your chances of dementia?

In this blog you will learn:

  • Why is sleep important for cognition?
  • What happens in the brain during sleep?
  • What are the consequences of not getting enough sleep?

In this blog series on sleep, we will look at cognition & sleep, the best diet for sleep, the best supplements for sleep, the circadian rhythm of sleep, sleep & light exposure, the importance of optimally aligning diet, light & the natural environment for sleep, and other fascinating information about sleep! 

WHY IS SLEEP IMPORTANT FOR COGNITION?

During sleep, the brain goes through different processes needed for good cognition, neuroplasticity, thinking, learning and memory consolidation.

Neuroplasticity:

Neuroplasticity is the brain’s ability to organize, adapt, reorganize and form new neural connections. 

Neuroplasticity changes happen continuously in response to learning new information, memory recall, having experiences or environmental changes. Sleep promotes synaptic or neuro-plasticity, as well as the ability of synapses (the connections between neurons) to change in strength and structure.

The brain needs sleep to perform neuroplasticity. Sleep helps to modulate different parts of the brain that create brain changes in response to learning. These include cortical, grey matter and white matter thickness and volume, synaptic structures and connections and myelin thickness (Stee W, 2021).

  • Intellectual ability and intelligence are related to brain structure including things like the thickness of the cerebral cortex and changes in cortical thickness, grey matter volume and thickness and white matter volume and thickness (Stee W, 2021). 
  • Learning a foreign language is associated with increased cortical thickness in different parts of the brain’s cortex, increased volume in the hippocampus and increased density in grey matter (Stee W, 2021). Changes in grey matter happen with other cognitive tasks like video game, golf or musical training, and learning conceptual knowledge or Morse code (Stee W, 2021). 
  • White matter changes happen alongside grey matter changes. White matter changes after cognitive exercises, including intensive reading training and learning a foreign language (Stee W, 2021). Both grey and white matter change structural plasticity and remodeling after learning new information.

The underlying mechanism for these changes is thought to be neurogenesis. This is when new neurons grow in the brain, existing neurons regenerate and become fully functional in response to learning. This process is mainly happening in the hippocampus (Stee W, 2021). 

Glial cells are also important for learning. After learning, glial cells increase due to gliogenesis in the cortex. In fact, glial cells outnumber neurons in grey matter by an approximate 6:1 ratio depending on the brain region (Stee W, 2021). Blood vessels make up about 5% of grey matter volume and vascular changes might also be involved in some grey matter modifications (Stee W, 2021). 

Memory Consolidation: 

During sleep, especially REM (rapid eye movement) sleep and slow wave sleep, the brain consolidates memories.  

The hippocampus of the brain replays and reinforces recently acquired information. In slow wave sleep, the brain transfers and consolidates information recently encoded and temporarily stored in the hippocampus into long-term memory stored in the neocortex (Grimaldi D, 2020). Part of this consolidation process involves synaptic changes (Klinzing JG, 2019). Synaptic changes, connections between neurons and systems memory consolidation processes happen in the hippocampus.

The process strengthens the connections between neurons involved in learning and memory. It integrates new information into neuronal networks and existing knowledge. 

Sleeping after learning new info is good for memory.  Sleep strengthens brain plasticity processes with changes happening to brain structures like grey matter volume and thickness, cortical thickness or white matter thickness. Neuronal networks are dynamic in sleep as this memory consolidation process is taking place (Stee W, 2021). 

It is thought that locally increased synaptic strength (connections between neurons) is downscaled to baseline level by NREM sleep (Stee W, 2021). This restores the neural space for future learning while consolidating new memories and information (Stee W, 2021). So, one function of sleep is to downscale increased synaptic strength that happens while being awake. This brings back synaptic balance and makes space for learning new information (Stee W, 2021).

Learning and consolidating new information is a primary function of sleep. But the other side of the coin is forgetting. Discarding and forgetting useless information is important to avoid overloading or overwhelming the brain. Memories go through a selection process during sleep. Depending on their importance, information such as events of the day go into either memory consolidation or forgetting (Izawa S, 2019). Forgetting removes unimportant and unnecessary memories by renormalizing and rebalancing synaptic connections. Forgetting is an active process. Specific neurons are either activated or inhibited, depending on whether something should be remembered or forgotten during sleep (Izawa S, 2019).

Learning New Skills: 

Adequate sleep is particularly important for learning new skills, adapting to new information and consolidating motor skills. It facilitates the new learning and helps to retain new knowledge and abilities.

White matter optimizes information transmission through myelin remodeling, involved in learning processes. Myelin remodeling occurs in response to changes in neuronal activity and is required for learning and memory. In research, increased myelination was seen in white matter connecting task-related areas in the brain after 4 weeks of motor training (Stee W, 2021). Tool-use training for 2 weeks led to new neural connections in adult monkey brains (Stee W, 2021). The pre-existing neural routes were fine-tuned and reinforced when learning new tasks (Stee W, 2021). 

Neurons and axons are active in the formation of new skills and functional memory (Stee W, 2021). When learning something, neurons in different parts of the brain communicate with each other. Neurons grow new projections and form new connections when the brain is learning. If two neurons frequently interact, they form a connection so they can transmit messages more easily and accurately. The brain may also produce new neurons (Stee W, 2021).

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Brain Repair & Maintenance: 

The brain’s glymphatic system is more active during sleep. The glymphatic system is responsible for detoxing the brain and clearing out toxins and metabolic waste products accumulated during waking hours. 

One important product removed from the brain in this process is beta amyloid protein. Beta amyloid is involved in the development of Alzheimer’s and other brain disorders. During non-REM sleep, the brain clears toxins, waste products and beta amyloid. 

In rodent studies, chronically restricting sleep is linked to increased beta amyloid in the brain (NIH, 2020). People with a history of sleep disturbances have abnormal deposits of tau tangles and beta amyloid plaques in their brains (NIH, 2020). Both tau tangles and beta amyloid plaques are found in Alzheimer’s, dementia and other neurological conditions. This demonstrates the importance of the glymphatic system and the repair process to maintain brain health and function. 

Synaptic Pruning & Growth: 

Part of the repair & cleaning up process includes synaptic pruning and growth. Sleep promotes synaptic plasticity, the ability of synapses (connections between neurons) to change in strength and structure. Sleep allows for the pruning of unnecessary connections and the strengthening of important ones, to optimize neural connections and improve cognitive function.

WHAT HAPPENS IN THE BRAIN WITH SLEEP DEPRIVATION?

Poor sleep, or sleep deprivation, has adverse consequences on cognitive performance and even behavior. Neurological pathways slow down, reaction time is reduced and mental state declines. Fluctuations in brain activity, synaptic activity, amygdala activity and hippocampal activity cause irregular activities in the brain to manage sleep deprivation. 

Sleep deprivation can have negative emotional consequences and lead to inappropriate behaviors. With a lack of sleep, amygdala activity is increased. Increased amygdala activity leads to decreased inhibition signals. This can make it difficult to make rational decisions and social judgements (Khan MA, 2023).

Sleep deprivation impairs memory formation and consolidation (Khan MA, 2023). It disrupts memory consolidation in the hippocampus, which is how a memory moves from an unstable to a more permanent memory. 

WHAT ARE THE CONSEQUENCES OF POOR SLEEP ON COGNITION?

In terms of performance, poor sleep can impair attentiveness, alertness, judgement, decision-making and other cognitive functions. Consistent inadequate sleep for multiple days causes the body’s systems to gradually decline, including brain and cognitive function. 

Dementia:

The risk of dementia and neurodegenerative conditions increases with sleep deprivation. Less sleep, changes to NREM sleep and disrupted sleep contribute to cognitive decline and neurodegeneration in aging (Grimaldi D, 2020). Alzheimer’s and Parkinsons diseases are associated with changes in sleep structure and circadian rhythm (Grimaldi D, 2020). Sleep changes also affect the severity of neurodegeneration (Grimaldi D, 2020). 

  • Older adults who sleep less than 7 hours a night and people with a high variability in sleep duration are more likely to show signs of cognitive impairment and cognitive decline (Keil SA, 2023).
  • Short sleepers (<7 hours per night) have significantly higher risk of cognitive impairment (Keil SA, 2023).

Sleep activates the glymphatic system to clear waste products, beta amyloid and tau proteins. Acute sleep deprivation slows this clearance, with the rate of metabolic substances and solutes clearance dependent on sleep. Chronic impairment of the glymphatic system could be why short sleep duration is linked to cognitive impairment (Keil SA, 2023).

In addition to more beta amyloid plaque, short sleep duration is also linked to faster ventricular expansion and worsening neurodegenerative processes (Keil SA, 2023). Ventricles are cavities within the brain, which cushion the brain to protect it from trauma. They remove waste, deliver nutrients to the brain and help maintain the CNS. The CNS is important for information processing, temperature regulation, thought, movement and much more.

Ventricles are a reliable and sensitive measure of brain atrophy and disease progression in dementia and Alzheimer’s (Manera A, 2022). The ventricles appear larger, or to have expanded, in comparison to atrophy seen in brain tissue. Ventricular enlargement measures track neurological changes associated with mild cognitive impairment (MCI) and Alzheimer’s. 

In one study (Nestor SM, 2008):

  • People with Alzheimer’s had greater ventricular enlargement compared to people with MCI and to people with no cognitive issues. 
  • People with MCI had a greater rate of ventricular enlargement compared to people with no cognitive issues. 
  • People with MCI who progressed to clinical Alzheimer’s after six months had greater ventricular enlargement than stable MCI subjects  (Nestor SM, 2008)

Lack of Focus:

Being sleep deprived decreases the ability to focus and concentrate. This weakens memory and may lead to forgetfulness and frequently misplacing things. The inability to concentrate on the immediate moment means that learning is affected as info will not make it into short-term memory and then long-term memory (Khan MA, 2023).

Reaction Time:

Slow reaction times due to poor sleep can be a problem when driving, working or doing tasks that require a quick response. It can be a particular concern for firefighters, police officers, soldiers and others who are often sleep deprived by their job but also need to have a quick reaction time.

Mood:

Lack of sleep can change and contribute to low mood. It causes irritability, anger and lowers resilience to stress. Tired people are more inclined to get upset in traffic jams and argue with other people. Chronic sleepiness increases the risk of depression. 

Sleep helps with pain and anxiety. Adequate sleep helps the brain to manage pain and anxiety through pain-relieving and anti-anxiety effects.

Healthy Lifestyle:

Sleep-deprived people are less likely to have the energy to exercise and eat a healthy diet. 

Over time, chronic sleep deprivation, impaired memory, low mood and other consequences of poor sleep can affect a person’s cognitive and thinking abilities, job and relationships. So, if you are having trouble sleeping or staying asleep, get in touch.

** Follow us for our next Blog on Sleep Strategies to Live Longer and Be Stronger through Diet, Lifestyle and a Functional Medicine approach **

SUMMARY

  • Sleep is vital for important cognitive functions, such as brain plasticity, memory consolidation, learning new information and brain repair processes.
  • The brain’s repair and clean-up process cannot function well on poor sleep. This has consequences for long term brain health.
  • If we don’t sleep enough, the risk of developing dementia or other neurological diseases increases. Other cognitive issues are a lack of focus or attention, poor memory recall, slower reaction times, low mood and potentially unhealthy lifestyle habits. 
  • Consult our previous blog on sleep here. It will help you to adopt a good sleep hygiene routine to consistently sleep well for good brain health. 

As always, please get in touch with us. If you or someone you know is struggling with sleep or cognitive issues, contact our clinic today. We can work on any issue(s) and improve your health. Book a free health evaluation call with us today. We can answer your questions and book an initial consult with a functional medicine doctor in our clinic.

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