sleep + stress: part II.

read time: 5-10 minutes.

table of contents.

  1. intro
    1. maladaptive resource allocation of chronic stress
      1. a broad term that defines the consequences of long term stress
    2. focus on sleep + stress
      1. minimizing stress and maintaining appropriate sleep architecture is critical for a well-oiled, healthy functioning body and optimal mind.  
  2. why we sleep
    1. conserve energy resources
    2. repair and rejuvenate
    3. brain plasticity
      1. memory, mood + emotion modulation
  3. circadian rhythm
    1. what is it?
    2. the processes it effects
      1. sleep/wake cycle
      2. cognitive function
  4. effects of stress on sleep
    1. circadian rhythm becomes off
      1. time it takes to fall asleep and stay asleep
        1. interrupted sleep cycle (waking up mid-sleep)
      2. disrupts deep sleep or rem sleep
      3. insomnia
    2. biological effects (deprivation or poor sleep)
      1. brain fog
      2. suppressed immune system
        1. lower defenses (cytokines to infections)
          1. higher risk of short term and chronic illness  
        2. increase in inflammatory cytokines
      3. increased cortisol/ caffeine and adenosine  
        1. stimulates and keeps you alert
        2. pattern t/o the day (biorhythm)
        3. inconsistent sleep schedules
  5. combat stress and support healthy sleep hygiene
    1. healthy diet and hydration
    2. exercise
      1. healthy stress
    3. minimizing stressors
      1. allowing your body to rest when needed
      2. screens
      3. food before bed
    4. improve your sleep environment
      1. comfort (mattress)
      2. create a space for sleep and only sleep

we’ve covered why sleep is a highly important, meticulously evolved function, so we’re now going to jump into why it is so difficult to come by these days. once these obstacles are reviewed, we’ll then dive into what happens to the body when these issues become chronic. this piece will wrap up with a couple of ways you can set up a supportive routine and hopefully make sleep #1 once bedtime comes calling.

effects of stress on sleep.

let’s think back to our first piece in the stress series to what happens biologically when stress is a constant. excess adrenaline and cortisol get produced in the brain, and since we’re in fof mode, many of our organs are working extra hard to keep us in an attentive state - even when your body thinks it should be winding down. maybe you have a very late shift or a thesis due in a few days - third cup of caffeine incoming. those caffeine molecules happen to fit right into the adenosine receptors (sleepy trigger) to keep you feeling more alert. so having an active sympathetic nervous system around the clock sure confuses the hell out of your internal clock.

external variables begin to not matter. internally, your body doesn’t understand that the sun going down means it should be getting tired when adenosine doesn’t seem to be triggering the brain and cortisol is keeping blood glucose levels higher than necessary. cortisol levels are naturally higher in the morning, getting our bums out of bed and going for the day. higher cortisol levels at odd times of the day throws everything off. with the circadian rhythm off, we start running into issues like longer times to fall asleep and not being able to stay asleep. quality of sleep may be affected as well, as without the proper amount of rem cycles we start to lose energy conservation and repair and rejuvenation processes.

how stress affects sleep

brain fog and its priorities.

as soon as there is disorder to our sleep architecture (poor sleep and/or deprivation), we start to see even further detriment. brain fog and a suppressed immune system follow on the coattails of stress-induced sleep problems. when we aren’t able to take that time to rest and rejuvenate our brains and bodies, we give up the time for brain plasticity. we lose the time for clearing out adenosine and we lose the time for tissues to do their repairs. not to mention the detrimental loss of peak glymphatic functioning to clear out brain waste. if we aren’t able to reach nrem stage 3 (n3) and rem, many necessary biological actions are lost and the overall health of the body and brain is severely compromised.

 

ever woken up after 8.5 hours of sleep and you still feel like molasses? you’re hungry all day, your brain can’t seem to make sense of any sentences and maybe you’re a little edgy. this is all due to a lack of deep sleep.

how stress affects sleep

higher vs. lower-level brain functioning.

without access to our deeper stages of sleep, our brains prioritize lower-level brain functioning as opposed to both lower and higher-level functioning during our waking hours. the lower-level brain consists of the following structures: brain stem, cerebellum, and spinal cord and are the brain’s oldest, primitive parts that evolved first. they mediate and control functions such as movement, respiration, sensory information, sexuality, eating and drinking. survival functions. our higher-level brain areas, however, have evolved over thousands of years and are what make humans unique.

you can think of these higher-level functions as cognition and behavior or executive functions. judgment, decision-making, intelligence, memory, speech, etc. since our bodies have limited resources for our executive functions when we don’t get quality sleep, we see less control over our emotions and rationalizations. the mind-body is stressed and tired, playing a further role in choking the connection between the lower-level and higher-level brain. reactivity, cravings and impulses (hunger and emotions) begin to dominate as we are more focused on keeping our bodies in a state of survival (lower-level brain functioning). proper amounts of time spent in stages 3+4 of our sleep cycle will provide our brains with the ability to rest and then properly allocate energy towards our higher-level brain functioning where we can optimize efficiency, productivity and creativity.

lack of sleep + the immune system.

with sleep deprivation, we also see a decrease in lymphocytes and the abilities of natural killer cells, which play a critical role in detecting and exterminating pathogens, like viruses. the integrin molecules that provide t-cells (lymphocytes) with their stickiness increase production during sleep. without sleep (specifically n3), our superstars of the adaptive immune system can’t exterminate foreign invaders properly. on the flip side of things, we see an increase in inflammatory cytokines, cells that are responsible for the first line of defense when an infection comes. this leads to excess inflammation and more physical issues ranging from joint pain to heart disease. our immune systems take a big hit when our biorhythms are confused and we aren’t able to reach a healthy amount of n3 + rem sleep.

combating stress for healthy sleep.

in our previous piece on long-term stress and the immune system, we scratch the surface of what can be done to combat this chronic stress. a healthy diet, hydration and exercise are some of our top recommendations that cut back on stress and help with the quality of sleep. that being said, without proper sleep hygiene, achieving that dream sleep can still be difficult.

while we’re on our way to rem, stopping in n3 is highly important. many of you have heard of our body’s lymphatic system, the system that is part of our immune system and the highway for white blood cells. we now give you: the glymphatic system. this system works tirelessly during n3 to increase cerebrospinal fluid (csf) flow and clear out any toxic cellular trash that has built up in the brain. when the brain isn’t able to take out the garbage, we see build-up of metabolites like amyloid-beta (a by-product of a protein that supports synapse formation and neural plasticity). amyloid-beta is considered plaque and is directly linked to neurodegenerative diseases like alzheimer's. further, looking back on our inhibition of neurotransmitters, the decline of norepinephrine is directly responsible for the increase of interstitial space in the brain. without the turning off of these neurotransmitters, there would be no increase in csf and therefore no clearance of toxic waste. there are consequences when n3 doesn’t thrive throughout the night.  

back off of screens.

in order to achieve excellent sleep hygiene, we have a few suggestions you can utilize right away — decreasing screen time is a biggie.

prolonged screen time or blue light exposure during the evenings triggers what are called intrinsic photosensitive retinal ganglion cells (iprg) in our retina (the back of our eyeballs). those iprg cells are responsible for regulating consciousness and sleep. when these cells are triggered, they depolarize (electrical charge shift) and cause suppression of the sleep hormone melatonin making it more and more difficult to fall asleep. cutting screen time at least two hours before bed will support the proper release of melatonin, and set your circadian rhythm on track.

how stress affects sleep

late night snacking.

along with screen time, let’s jump into late-night snacks. while you might think a full stomach will rock you to sleep, it can be detrimental to the energy conservation process we chatted about in our first stress and sleep piece. not to mention falling asleep will be very difficult.

our bodies specifically draw energy away from processes like digestion to focus more on sleep-dependent functions such as brain plasticity. when you eat something right before bed, your body puts more focus on digestion, leaving memory, tissue repair, and immune-boosting on the back burner. if you try to make your last meal around 3 hours before bed, your body will have the proper time to digest and will then make sleeping (with all its happenings) a priority.

make it cozy.

our last and highly significant suggestion involves keeping a healthy sleep environment. creating a space specifically for sleep is often something that gets overlooked.

just like our cues from the sun, having a dark room with a comfortable, supportive mattress+pillows helps trigger our bodies into a restful slumber. it keeps our biorhythms in a routine. if we spend too much time in the bedroom during the day or are on our screens while lying in bed, our brains will have trouble registering where to find that sought-after deep rest.

we find that a cozy bed and an evening read do just the trick.

definitions.

circadian rhythm.

the circadian rhythm is a biological clock that responds to internal + external cues and regulates the human sleep-wake cycle. during this cycle, there are physical, mental, and behavioral changes that occur. this entire cycle is roughly 24 hours.

starting in the morning, there is an increase in the hormone cortisol which causes alertness. when cortisol is released, melatonin (sleep hormone) is inhibited. there is an increase in blood pressure first thing in the morning and heart rate, respiration and digestion ramp up from lower levels during sleep.

throughout the day alertness, coordination, reaction time and body temperature increase as the body burns through atp energy molecules. when atp is broken down by the brain, the by-product adenosine builds up and fits into receptors that let the brain know it is getting tired from burning energy. the more atp used→ the more adenosine builds up→ the more tired you become. this usually happens around the late afternoon/evening when the body is also getting external cues from the sun that it is time to wind down.

once the eyes stop receiving blue light from the sun, there is no longer inhibition of melatonin and the hormone begins to release. melatonin secretion gradually increases right after darkness, reaching a peak in the middle of the night (around 2am-4am). from there, melatonin begins to decrease up until the release of morning cortisol.

during sleep, the body reaches it’s lowest temperature, blood pressure, heart and respiration rate. brain activity slows down at the beginning stages of sleep and spikes during rem stage. brain plasticity and the immune system are highly active during sleep hours.

humans have evolved to sleep as it is a way for the body and brain to repair, rejuvenate and conserve energy. this evolution has been fine-tuned over thousands of years so that the human species can survive and thrive at peak capacity.

glymphatic system.

a unique system in the brain that uses specialized tunnels, called perivascular tunnels or space, cerebrospinal fluid (csf) and interstitial fluid to clear out neurotoxic waste products that build up in the brain. this system is the most active during the third stage of nrem sleep (n3) and is mostly inactive during waking hours. when the body and brain reach n3, the flow of fluid increases from 15%-24% and clearance of waste is expedited. without significant time spent in n3, the glymphatic system is unable to take out the cellular garbage and *neurodegenerative diseases can ensue.

*research shows that the glymphatic system is responsible for clearing our metabolite plaque such as aamyloid-beta, which is responsible for the neurodegenerative disease alzheimer’s.

maladaptive resource allocation.

the body's process in which valuable energy resources are diverted away from crucial biological processes (immune system, digestion, detoxification, neurogenesis, etc.) in order to fuel the fight-or-flight response that is triggered by the sympathetic nervous system. maladaptive resource allocation happens overtime when the body and brain are chronically stressed as energy is consistently being utilized to support processes like increased heart rate and breathing, muscle strength, heightened vision, and a shift towards the instinctive, reactive part of the brain. overtime, there is massive imbalance in the body as homeostasis is constantly being disrupted by the stress response

stages of sleep.

when we sleep, we go through stages. we then go through cycles of all the stages. nrem1→ nrem2→ nrem3 → rem. this cycle is repeated around six times per night and lasts about 90 minutes. although on average, each stage consists of 25% of the cycle, it does vary throughout the night. 8-9 hours of these cycles is considered the optimal amount of sleep, however, it should be noted that it is necessary to get a quality amount of certain stages (3+4) in order to feel rested and ready to go. below are the names of the stages and what is happening to the body and mind when we go through each stage.

non-rapid eye movement stage 1 (nrem 1): doze off stage. there might be some twitching as the muscles relax. the brain and body functions, as well as eye movements, begin to slow down. brain waves also begin to slow down in comparison to the active patterns during the day.

non-rapid eye movement stage 2 (nrem 2): light sleep stage. brain, body, and muscles start to slow down and relax even further. eye movement slows, then stops and the body’s temperature begins to drop. brain waves are even slower than in nrem 1, marked by larger brief pulses leftover from daytime activity.

non-rapid eye movement stage 3 (nrem 3): deep sleep stage. it is almost impossible to wake someone up in this phase. heartbeat and breathing are at their slowest and there is no eye movement. brainwaves are the longest and slowest in comparison to other stages. as to reasons why we sleep, many of them happen in this phase.

in the brain, specific neurotransmitters are turned off (norepinephrine, serotonin, and histamine) so that they are able to regain sensitivity and work at peak capacity during waking hours. the temporary retirement of norepinephrine triggers the glymphatic system to go into action. the glymphatic system is the brain's waste removal system. it clears out any toxic waste that has accumulated during the day, including adenosine, a byproduct of atp (energy molecule). adenosine builds up throughout the day and lets the brain know it’s burned through lots of energy and is now tired. in order to feel clear-headed, these adenosine molecules need to be cleared out and the glymphatic system is the one to do it!

elsewhere in the body, the immune system is getting a boost. integrin production increases. these are proteins that provide t-cells (adaptive immune system fighters) with their stickiness to latch onto invaders. without nrem3, t-cells lose much of their ability to attach to and eliminate unwanted foreign molecules. due to the boost during this stage, tissues and muscles are also receiving extra attention for repair. whether you’ve been working out or have an injury, nrem3 is when those repairs are attended to.

nrem3 is the hardest stage to consistently get as many factors can prevent the body and brain from entering this stage. take sleeping in a hotel room for example. the brain is aware that you are in an unknown space, and due to the evolution of survival, the brain needs to be on alert just in case there’s a threat. since nrem3 is the deepest sleep (and near impossible to wake someone up from), the brain chooses to not spend as much time in this stage.

a couple more examples include coffee and artificial blue light. both of these are mechanisms that prevent sleep triggers from occurring in the brain. with the delay of sleep triggers, the sleep cycles get pushed back and we aren’t able to spend the time we need in the important stages (nrem3 and rem). without quality time spent in these stages, the biological processes mentioned above occur less, which in turn causes detrimental consequences to our overall health.

references.

  1. cdc. (2020). module 2. sleep and the immune system. centers for disease control and prevention. retrieved from: https://www.cdc.gov/niosh/work-hour-training-for-nurses/longhours/mod2/05.html.
  2. rodnitzky, r. l., tranel, d., & cooper, g. (2003). higher brain functions . higher brain functions. retrieved from: https://link.springer.com/chapter/10.1007%2f978-1-59259-371-2_29
  3. tosini, g., ferguson, i., & tsubota, k. (2016). effects of blue light on the circadian system and eye physiology. molecular vision. retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4734149/.

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