Those who chronically get under seven hours of sleep a night are three times as likely to develop the common cold as those who regularly get at least eight hours. On average, more than one-third of U.S. adults don't meet sleep recommendations and get less than seven hours of sleep per night. Deep, restorative sleep is a foundation for good health; research shows that those who suffer from sleep disorders or chronically get insufficient sleep are at higher risk of having weaker immune systems and getting sick.
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The Basics of Sleep
Sleep is a natural, recurring state of altered consciousness and reduced sensory activity essential for the overall well-being of humans and many animals. It is a complex physiological process characterized by distinct stages, each serving different functions. There are two primary categories of sleep: non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. (11)
NREM sleep consists of three stages: N1, N2, and N3. N1 is the transition phase between wakefulness and sleep, characterized by light sleep and easily disrupted by external stimuli. N2 is a deeper stage where brain waves become slower, and sleep spindles and K-complexes appear. N3, known as slow-wave sleep, is the deepest and most restorative stage. It is essential for physical restoration, memory consolidation, and overall well-being. (5)
REM sleep is a unique stage marked by rapid eye movements, increased brain activity, and vivid dreaming. During REM sleep, the body experiences muscle atonia, preventing physical movement and ensuring dreams remain internal. This stage is crucial for cognitive function, emotion regulation, and learning. The sleep cycle typically progresses through these stages in approximately 90-minute cycles throughout the night, with more extended periods of REM sleep occurring later in the sleep cycle. (5)
Two internal biological mechanisms work together to regulate when you are awake and sleeping. The first is the circadian rhythm, controlled primarily by the body's 24-hour internal clock. The suprachiasmatic nucleus (SCN), a cluster of cells within the brain's hypothalamus, receives external light cues and controls melatonin and cortisol production to regulate the sleep-wake cycle. The second mechanism is sleep-wake homeostasis, which keeps track of the need for sleep and regulates sleep intensity. Sleep disorders can result when factors – including medications, stress, sleep environment, and light exposure – dysregulate either of these mechanisms. (5)
Before the 1950s, people believed sleep was a passive activity during which the body and brain were dormant; however, this belief has since been negated, and we now understand the brain actively engages in many activities necessary for life and health during sleep (33). Sleep requirements change throughout the lifespan. Babies initially sleep up to 18 hours per day. By adulthood, the recommended amount of sleep is 7-9 hours nightly. Unfortunately, about one-third of the American adult population reports not getting enough sleep.
The Immune System: A Vital Defense Mechanism
The immune system is a complex network of cells, tissues, and organs that is fundamental in safeguarding the body against harmful pathogens such as viruses, bacteria, and fungi. Its primary functions are to identify and recognize foreign substances, distinguish them from the body's own cells and tissues, and then mount a coordinated defense to eliminate or neutralize these invaders. The immune system achieves this through various mechanisms, including the production of specialized proteins called antibodies, the activation of immune cells like T cells and B cells, and the coordination of immune responses to ensure a targeted and effective defense. Additionally, the immune system possesses memory, enabling it to "remember" previously encountered pathogens, thereby providing immunity against future infections. (19)
When the immune system isn't functioning properly, complications arise. If the body's frontline defense against pathogens fails, overactivation of immune components develops, or the loss of self-tolerance occurs, health conditions including infection, allergies, autoimmune disease, and cancer develop. Various biological and environmental factors can weaken and dysregulate the immune system. Common factors include genetics, immune-suppressing medications, malnutrition, excessive alcohol consumption, intestinal dysbiosis, chronic stress, and inadequate sleep (19).
Sleep and Immune Function
The link between sleep and immune function is a critical and intricate one, with sleep playing a pivotal role in maintaining the body's ability to defend itself against infections and nurture a healthy immune system. Sleep and the immune system have a bidirectional relationship: active immune responses can affect sleep and vice versa. Over the years, evidence has emerged to support the notion that adequate sleep strengthens the immune system. In contrast, sleep deprivation contributes to a person's short- and long-term risk of getting sick. In short, science strongly indicates that sleep deprivation can make you sick. (29)
Why is this? During sleep, the immune system increases the production of cytokines, chemical proteins that help regulate immune responses. This cytokine production is essential in fending off impending infections, but research has also indicated this nighttime immune activity acts to strengthen the adaptive ("memory") subset of the immune system. Conversely, insufficient or poor-quality sleep reduces the production of immune cells and antibodies, weakening the immune system and making the body more susceptible to infections. (16, 21)
Additionally, insufficient sleep causes increased secretion of cortisol. Cortisol, especially when chronically elevated, impairs immune function by inducing apoptosis (programmed cell death) of T cells, suppressing B cell antibody production, and reducing other immune cell functions during inflammatory immune reactions. (3, 32)
Sleep is an important factor that increases vaccine efficacy; studies of vaccines for hepatitis and influenza have found that sleep deprivation before and after vaccination reduces the body's immune response to the vaccine, reducing its effectiveness in disease prevention.
Not only is the circadian rhythm responsible for managing a healthy sleep-wake cycle, but research has also connected it to the control of allergic reactions. Therefore, we can assume circadian disruption may increase the likelihood of developing allergies. One study that has supported this theory demonstrated that sleep deprivation reduced the allergen threshold in patients with peanut allergy by 45%, making them more susceptible to having an allergy attack.
Other research shows that a consistent lack of sleep, defined as losing just one and a half hours of sleep nightly, upregulates inflammatory immune responses and systemic inflammation. Chronic inflammation has been associated with many disease processes, including cancer; diabetes; depression; neurodegenerative disorders; and cardiovascular, autoimmune, liver, and kidney diseases.
Functional Medicine Labs to Assess Sleep and Immune Function
Along with a sleep study, functional medicine labs help practitioners identify the causes of sleep disturbances, assess immune status, and personalize treatment options for their patients struggling with poor sleep and symptoms of a lowered immune system.
Sleep & Stress Hormones
A salivary sleep and stress panel measures diurnal patterns in melatonin and cortisol levels. Alterations from standard patterns can result from and contribute to sleep disorders and illness.
Neurotransmitters
Neurotransmitters play a crucial role in regulating the sleep-wake cycle and controlling the transition between wakefulness and the different stages of sleep. Neurotransmitters are also partially responsible for modulating immune responses. Therefore, a neurotransmitter panel can be an important specialty lab to consider ordering to evaluate sleep patterns and immune function. (14, 28)
Immunoglobulins
Measuring total immunoglobulins is used to assess immune function. Total immunoglobulin measurement quantifies the IgM, IgA, and IgG antibody levels in a person's blood. Low levels may suggest an immune deficiency, making individuals more susceptible to infections.
Lymphocyte MAP
The Lymphocyte MAP test is a newer test on the market that better measures the integrity of the immune system by identifying various immune cell patterns. This test helps to provide practitioners with a detailed picture of underlying conditions and specific imbalances within the immunological cascade triggering health conditions related to immune dysfunction.
Inflammation
Inflammation markers, including hs-CRP and ESR, can quantify systemic inflammation that may be triggered by sleep deprivation and help estimate the risk for various chronic diseases.
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Integrative Medicine and Sleep
Integrative medicine approaches sleep issues by recognizing that these problems often stem from a complex interplay of physical, mental, and lifestyle factors unique to each individual. Rather than employing one-size-fits-all solutions, integrative medicine emphasizes an individualized treatment approach. It considers not just the symptoms but also the underlying causes of sleep disturbances. Integrative practitioners may combine conventional medical therapies with complementary approaches such as acupuncture, mindfulness-based stress reduction, dietary changes, and cognitive-behavioral therapy for insomnia. This holistic approach addresses the immediate sleep problem and the patient's overall well-being, aiming for sustainable improvements in sleep quality and duration. By tailoring treatment plans to each patient's specific needs and circumstances, integrative medicine offers a more comprehensive and personalized approach to tackling sleep issues, ultimately promoting better sleep and overall health.
Lifestyle Factors That Impact Sleep and Immunity
Below are some complementary and integrative modalities that functional medicine providers will use to create holistic treatment plans for their patients to optimize sleep and support the immune system.
The Influence of Diet on Sleep and Immunity
A well-balanced and nutrient-rich diet can support both sleep and immune function. Prioritizing whole foods, minimizing processed and inflammatory foods, and paying attention to meal timing is essential to promoting a healthy relationship between diet, sleep, and immunity.
Chronic inflammation, often linked to a diet high in processed foods, sugars, and unhealthy fats, can negatively affect sleep and weaken the immune system. Inflammation can disrupt the production of sleep-regulating hormones and cytokines, leading to sleep disturbances and an increased risk of infections. (19)
The gut microbiome, influenced by diet, plays a crucial role in immunity and sleep. An imbalanced gut microbiome can lead to digestive issues, inflammation, and sleep problems. A diet rich in fiber, prebiotics, and probiotics supports a healthy gut, which, in turn, positively impacts immune function and sleep regulation. (18)
Eating high-sugar, refined carbohydrate foods can cause rapid spikes and crashes in blood sugar levels. These fluctuations can disrupt sleep by causing nighttime awakenings and weaken the immune system over time. (8, 26)
The consumption of caffeine and alcohol can interfere with sleep patterns. Both substances can disrupt the natural circadian rhythm and reduce the overall quality of sleep, making it more challenging for the body to maintain immune health. Avoidance or restricting consumption of either drink, especially in the afternoons and close to bedtime, is recommended. (8)
Supplements and Natural Remedies for the Immune System and Sleep Balance
Many natural supplements can support the immune system and sleep quality. To get the most bang for your buck, consider using a couple of options that have been proven to support healthy immune function and sleep patterns.
Research suggests that vitamin D may influence sleep patterns by playing a role in regulating the body's circadian rhythm and sleep-wake cycle. Adequate vitamin D levels are also associated with improved immune function, as it plays a crucial role in activating immune cells and the body's defense against infections.
Melatonin supplementation is commonly used to address sleep-wake disorders. Supplemental melatonin effectively reduces the time it takes to fall asleep and improves sleep duration and quality. Melatonin also has some potential implications for immune function, with studies showing its ability to modulate and strengthen immune responses to protect the body against infectious pathogens and cancer.
The Role of Physical Activity in Promoting Better Sleep and Immunity
Research indicates that engaging in regular, moderate-intensity exercise can improve sleep patterns and promote better sleep quality. Exercise can reduce the time it takes to fall asleep, increase the duration of deep sleep, and decrease the frequency of nighttime awakenings.
Regular exercise is associated with enhanced immune function. It can help increase the production and circulation of immune cells, such as T cells and natural killer (NK) cells, which play crucial roles in defending the body against infections. Exercise also reduces chronic inflammation, a state linked to weakened immunity. (23)
When exercise and sleep are optimized together, their synergistic effects on immune function can be particularly beneficial. Regular exercise can promote better sleep, and improved sleep quality, in turn, can enhance the immune response. This positive feedback loop contributes to overall immune resilience.
Improving Sleep for a Stronger Immune System
Sleep hygiene refers to a set of practices and habits that promote healthy and restorative sleep. Good sleep hygiene is essential for maintaining overall well-being and ensuring you get the rest your body needs. Here are some key components of sleep hygiene:
- Go to bed and wake up at the same time every day, even on weekends. Consistency helps regulate your body's internal clock, making it easier to fall asleep and wake up naturally.
- Make your bedroom conducive to sleep by keeping it cool, dark, and quiet. Invest in a comfortable mattress and pillows, and remove any disruptive sources of noise or light.
- The blue light emitted by smartphones, tablets, computers, and TVs can interfere with your sleep by suppressing the production of melatonin, a hormone that regulates sleep-wake cycles. Avoid screens at least an hour before bedtime.
- Avoid heavy or spicy meals close to bedtime, as they can cause discomfort and disrupt sleep. Minimize the consumption of liquids in the evening to reduce the likelihood of waking up to use the restroom at night.
- Practice relaxation techniques such as deep breathing, meditation, or progressive muscle relaxation to reduce stress and anxiety, which can interfere with sleep.
- While short naps can be rejuvenating, long or irregular daytime naps can disrupt nighttime sleep. If you nap, keep it brief (20-30 minutes) and earlier in the day.
- Use your bed primarily for sleep and intimate activities. Avoid working, watching TV, or using electronic devices in bed to strengthen the association between your bed and sleep.
- Exposure to natural sunlight during the day helps regulate your circadian rhythm and reinforces your body's natural wake-sleep cycle.
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Summary
The relationship between sleep and immune function is complex, but research overwhelmingly suggests a bidirectional relationship between the two. When one is compromised, so is the other. Sleeping well is essential to ensuring a healthy immune system and preventing disease. Improving sleep starts with focusing on lifestyle habits and sleep hygiene. People with chronic sleep issues should talk with a doctor to discuss additional labs, testing, and integrative medicine options that can further help them get a good night's sleep and strengthen their immunity.
Lab Tests in This Article
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