immunodeficiency. Reduced sleep re-sulted in a lowered response to vacci-nation to influenza virus, it also in-creased the susceptibility to the common cold. Sleep not only impacts primary responses to infection, it also impacts the formation of antigenic memory(3). Getting 8 hours of quality sleep in-fluences levels of systemic inflamma-tion and immune system function. Several studies have already confirmed the negative effects increasing levels of inflammation has on immune health. Irwin and Opp(4) reviewed substan-tial evidence supporting the homeo-static relationship between sleep dis-turbances and inflammatory disease risk. Circadian rhythm is linked to quality sleep. Circadian rhythm disrup-tions magnify inflammatory responses to endotoxic challenge. Chronic jetlag and shift work displayed an upregula-tion in inflammatory gene expression. Those suffering persistent sleep loss (insomniacs, alcoholics, stress, aging) show a shift to enhanced proinflamma-tory cytokines not just temporarily but constantly(3). Sleep has stages we pass through in a sequential order with individual var-iability in how long we spend in each stage. Slow wave sleep (SWS) known as stage 3-4, is deep restorative sleep. This is the time our bodies are healing, repairing, and conducting surveillance Disturbances such as inflammation or circadian rhythm disruption reduces SWS and increases REM sleep (less deep sleep and more dream sleep) re-sulting in a decrease in immune re-sponse and increasing risk for infec-tions. Proper immune surveillance becomes disrupted with poor sleep. Insomniacs show a decrease in immune T cells (CD3+, CD4+, CD8+) and a reduction in natural killer cell activity (3). These alternations impact the abil-ity of the immune system to respond to a challenge. The greatest amount of time in SWS occurs in the first part of nocturnal sleep and declines as the night contin-ues. Retiring around 10pm has been shown to increase time spent in SWS restorative sleep. There appears to be a sweet spot as to when you should go to sleep. There is often a window of op-portunity to pay attention to. It’s not uncommon to feel a bit sleepy around 9-10pm and then after this time has passed, a second wind of wakefulness hits. It would be better to capitalize on the time you start to feel sleepy to get into your rhythm and grab those early SWS hours. Another mechanism sleep and im-mune health are connected is through T-cell adhesion and the role of integrin. An effective T-cell response to a vi-rus-infected cell is through its binding ability to the infected cell via integrin. In a study comparing those who slept all night vs those who stay awake, sleep up-regulated integrin activation com-pared to nocturnal wakefulness, an important mechanism sleeps exerts an immune-supportive effect(5). Whether through inflammatory ho-meostasis, immune cell activation, or immune signaling, healthy sleep posi-tively impacts the immune response in several ways and should therefore not be dismissed in its importance. What exactly constitutes healthy sleep? It is not just the number of hours that dictate this. It has already been discussed how important time spent in deep restorative sleep is but simply focusing on the right number of hours it is a good starting point for most. Interestingly it has been demonstrated the benefits of sleep are a U-shaped curve. Those consistently sleeping <5 hour per night have increased risk of mortality while those sleeping > 9 hours per night also had an increased risk. It has been suggested those sleep-ing >9 often have comorbidities includ-ing heart disease, diabetes etc. The sweet spot for ideal sleep time appears to be between 7-8 hours per night(2). This once again brings us back to the basics we have heard over the years but now the mechanisms are being uncov-ered. Just because something seems to be simple, it does not always translate into action. In our busy world if sleep is not given the respect and priority it deserves, it is easy to fall short. STRESS Likely everyone can relate to the rela-tionship high stress may have on health. Stress produces elevated levels of stress hormones such as adrenaline and cortisol. High levels of these hormones interfere with sleep, while at the same time, reduced sleep(<7hr/night) causes a fight or flight stress response, further elevating the stress hormones and fur-ther interfering with sleep. This be-comes a perpetual escalating cycle; el-evated stress creates poor sleep which then further perpetuates the stress re-sponse. The concept of stress impacting one’s immune system health is not a new one, in fact in 200 AC Galenus suggested those suffering from melan-choly were more likely to suffer with cancer than those who were positive and exposed to less stress. Further suggestion of the stress-immune con-nection came in the 1920’s when it was concluded that those living with stress had increased risk of developing tuber-culosis. This idea continued to grow and in the late 1960’s researchers con-nected that those experiencing sudden, major stressful life changes had a greater probability of disease(6). We have come a long way in under-standing the mechanisms of how stress impacts immune health. It is importat to recognize not all stress produces a negative immune outcome. An acute stress response can be lifesaving. We are inherently pro-grammed to respond effectively to an immediate stress through our flight or fight response which can result in im-mune-boosting effects to fight off pathogens. Our well intentioned hypo-thalamic-pituitary-adrenal (HPA) ac-cess is meant to respond with various chemicals and hormones which after a period of time resolve and return to a healthy set point of homeostasis. Today we are living in a fast-paced treadmill of life where this acute stress response, meant for a short burst immediate threat, becomes ongoing and chronic, despite the lack of any true threat. How a stressor is perceived by an individual is very influential. Perceived psychological stress can down-regulate parts of the cellular immune response. If fact, it has been shown both stress and depression can decrease cytotoxic T-cell and natural killer cells, affecting immune surveillance, potentially af-fecting the development and progres-sion of tumours(7). Academic stress has been an interest for many researchers. Studies have demonstrated exam stress in university students resulted in reduced natural killer cell activity which also correlated with a degree of loneliness. This type www.Cndoctor.ca 14 Chiropractic and Naturopathic Doctor December 2020
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