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Relationship Between Sleep and Immune System Health

Sleep is the body’s mechanism to rebalance itself and restore health. The downtime gained by sleeping allows the body’s metabolic systems to heal themselves and, in doing so, organs, cells, and tissues are allowed to regenerate and rejuvenate. It is no wonder then that high quality sleep has a profound effect on immune health, on both innate and adaptive immunity, the two key arms of the immune response. Whether directly influencing the immune system’s ability to detect and eliminate immune challenges or by decreasing stress and normalizing cortisol levels, sleep is a powerful tool to strengthen the immune response.

The relationship between sleep and its effects on immune health is an area of increasing interest for researchers. It is critical not to overlook the importance of sleep. Studies show that sleep can enhance the production of several cytokines an aid the immune system’s interaction between antigen presenting cells and T helper cells. Sleep also improves the immune system’s ability to form immunological memory, a phenomenon whereby the immune system is more effectively able to recognize foreign bacteria and viruses and mount an efficient response. There is even evidence that immune activation and the proliferation of pro-inflammatory processes which are designed to negate offending pathogens are most active during the resting period, i.e., during sleep. A reason for this could be that, if these processes were most active during the day, it could lead to feelings of fatigue and malaise. Also, the body is much more able to divert energy and other resources to immune activation when the body is at rest, specifically when such resources are not being used by other processes.

An additional benefit of immune activity and inflammatory processes taking place at night is that this is also the time when secretion of melatonin is at its peak. Melatonin is an effective antioxidant and free radical scavenger. Since immune activation and inflammation lead to generation of free radicals, by having these processes highly active during sleep, melatonin and other antioxidants can more readily scavenge these free radicals, limiting and countering the oxidative stress that is proliferated. For these and other reasons, sleep is intricately linked to an effective immune system.

Can Sleep Deprivation Make You Sick?

Sleep issues such as insomnia as well as other lifestyle-induced sleep disorders are continuing to increase in prevalence. This was evident to a great extent during the pandemic. Studies show that individuals experiencing sleep deprivation are at increased risk of psychiatric conditions such as depression, anxiety, and substance abuse. Improving sleep and enhancing sleep quality is of utmost importance for supporting health. Understanding key contributors to the body’s sleep process are essential to effectively improve sleep quality. One of the key physiological factors in the body’s sleep cycle is the hormone melatonin.

Melatonin is the primary hormone secreted by the pineal gland of the brain and is known to act as a powerful “chronobiotic”, which means that it functions to maintain a normal circadian rhythm.

Melatonin production is inhibited by exposure to light and is stimulated during periods of darkness. The main signal for the pineal gland to produce melatonin is sensed through the neural pathways connected to the retina of the eye. If the retina senses darkness, melatonin production is signaled. A common modern concern that factors into deficient production of melatonin is exposure to blue light from digital devices. Sleep disturbances stemming from the use of cell phones, tablets, and computers, especially at night, are a real issue for many people.

Melatonin levels have been found to decrease with age, but several other contributors to low levels of melatonin exist. These including medications that suppress melatonin (including NSAIDS, beat-blockers, aspirin, and others) as well as factors that lead to poor sleep hygiene, including consumption of alcohol, caffeine, and nicotine.

Addressing the factors in our environment that impact our sleep, as well as other health issues that are present, is a first step in addressing issues we experience around poor sleep as well as why many of us have poor immune function.

Melatonin Benefits for the Immune System

Given the current climate where immune challenges are plentiful, research around melatonin’s effects for immune function is increasing. Studies have highlighted the antioxidant, free radical neutralizing, immune modulating, and anti-inflammatory effects of melatonin.

One of the major issues with certain viral infections is not the direct effect of the virus on the immune system; rather, the way our immune system responds and wreaks havoc on the body can be more detrimental. One of these phenomena is what researchers term the “cytokine storm”. This is defined as an upregulation of pro-inflammatory cytokines, which are chemical messengers of the immune response, leading to activation of neutrophils, macrophages and histamine containing mast cells. Uncontrolled activity of these cells on the body result in damage to key organs and systems and uncontrolled inflammation. Melatonin may effectively counteract this inflammation through several pathways, resulting in a reduction of pro-inflammatory cytokines being released. Moreover, melatonin can shift the balance more favorably towards an anti-inflammatory effect, resulting in protection of key organs and a balanced immune response.

During this exaggerated inflammatory immune response, an excess of free radicals is created. Melatonin is a powerful antioxidant that counteracts free radicals in three unique ways: 1) Melatonin acts directly as an antioxidant and powerful free radical scavenger; 2) Melatonin undergoes metabolism to byproducts that have high antioxidant activity; 3) Melatonin stimulates the production of antioxidant enzymes, while inhibiting the production of pro-oxidant enzymes.

Further research indicates that melatonin is directly involved in the control of antiviral and other immune pathways in the human immune system, while providing added protection to cells as a mitochondrial antioxidant. Interestingly, melatonin is abundant in the mitochondria of cells and can even be synthesized there. As immune challengers such as viruses initiate damage to cells, melatonin counteracts this to prevent cellular senescence and death.

This research strongly indicates the link between melatonin and immune system function. The research on sleep and immune function further solidifies the connection between the two areas and how melatonin plays an integral role in improving the function of both. Healthy sleep and a robust immune response go hand in hand; melatonin is an important link bringing the two areas together.

Stress and the Immune System

Sleep deprivation leads to increased stress on the body as cortisol levels remain constantly elevated. The interplay of stress on the immune system is complex. Studies have shown that short-term stress has several beneficial effects on immune function. Defined as stress lasting mor minutes to several hours, short-term stress can lead to an immune protective reaction. However, long-term stress is problematic because of its persistence. Most often, the effects of long-term (chronic) stress are detrimental to immune function and lead to immune pathology and immune suppression. This leads to increased inflammation and autoimmune disease, while decreasing the ability of the immune system to resist infections.

Chronic stress can lead to profound changes in the ability of the immune system to respond. Long-term stress can decrease the mobilization of white blood cells to the site of the immune response and suppress the ability of the immune system to produce antibodies fighting infection, reduce the activity of various immune cells such as NK (natural killer) cells and macrophages, and accelerate immune-senescence (the aging of the immune system leading to a decline in immune function).

Unfortunately, chronic stress has significant personal and health-related costs and is experienced widely in in the population. One of the big contributors to the chronic stress that most Americans experience is work-related stress. The effects of chronic stress on the immune system lead to much bigger consequences than just decreased immune function. Research suggests that chronic stress contribute to the development of cancer, autoimmune conditions, inflammatory conditions, and other chronic disease.

Fortunately, there are effective ways to combat the effects of chronic stress. These include the basics of ensuring you get adequate sleep, eat a balanced and nutritious diet (low in sugar and other processed foods), and get plenty of exercise. Activities such as yoga, walking, meditation, and mindfulness increase the body’s resilience to psychological and social stress, enhance immune function and improve health.

Furthermore, several supplements are useful for helping the body reduce stress. Some key herbal and nutritional factors for reducing stress include ashwagandha, the amino acid GABA, and the essential mineral magnesium. Taking these nutrients in combination can help the body cope with the negative effects of stress.

Addressing stress and improving sleep are foundational steps that we can take to improve our body’s immune response. Keeping in mind simple lifestyle factors that impact these areas as well as making smart choices with the stress and sleep supplements we take, it is possible to effectively improve sleep and enhance immune health.



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