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Immune System: The Role of Sleep

The role of sleep for good health is highly underrated. Due to the fact that it is a natural part of our daily routine we tend to take it for granted. Research on sleep suggests that it plays a crucial role for a strong immune system. It wards off infection, reduces inflammation and ensures an optimal immune response against potential disease causing pathogens. Additionally, along with diet and exercise, sleep is a key factor in keeping the immune system in check. As a part of the series on the immune system, readers are encouraged to explore the role of exercise and the immune system. More details on the basics of immune system and role of protein can be found in an earlier article.

How Sleep Affects the immune system?

A good night’s sleep is one of the critical factors for good immunity. During sleep our body releases cytokines. As discussed in an earlier article , cytokines play an important role in stimulating or inhibiting the inflammatory response of our body. They also prevent the body from attacking its own healthy cells. Sleep deprivation may inhibit production of cytokines.

Additionally, sleep plays a crucial role in improving T-cell functioning. When we sleep the stress in our body is decreased. Hence , a good night’s sleep ensures that T-cells function properly. T- cells are a type of white blood cell which is critical to our body’s immune response. When a T-cell recognizes that one of our body’s cells is infected with a virus it activates a sticky protein known as integrin. The integrins attach themselves to the virus infected cell and kills it.

Researchers at the University of Tubingen compared the integrin levels in sleep deprived and sleep activated individuals. It was observed that the signaling molecules which activate the integrin response was enhanced during sleep. “Our findings show that sleep has the potential to enhance the efficiency of T cell responses, which is especially relevant in light of the high prevalence of sleep disorders and conditions characterized by impaired sleep, such as depression, chronic stress, aging, and shift work,” according to one of the researchers Luciana Besedovsky.

The following flow chart in Fig 1 elucidates the relationship between sleep, stress and immune system.

Fig 1: Flowchart demonstrating connection between sleep and body’s immune response. Figure from Sleep and Health Chapter 24,2019 by Aric A. Prather

Sleep and Cardiometabolic Disorders

Lack of sleep has not only been associated with lower immunity but also an increased risk of chronic diseases. With the growing rates of insomnia and sleep apnea one begs the question are humans getting enough sleep ? The average adult requires 7-9 hours of sleep and contrary to popular belief you cannot “make up” for lost sleep. Stress hormones increase when we do not sleep enough. The following figure , explains how lack of sleep plays a crucial role in increasing the risk of cardiometabolic disorders. It should be noted especially during the COVID-19 pandemic, those with a previous history of cardiometabolic disorders have a higher fatality rate. Hence, it is imperative to reduce the risk of all cause mortality by taking steps to prevent the onset of these diseases. A good night’s sleep goes a long way, along with a healthy diet and exercise in reducing risk of chronic diseases.

Figure 2. Possible association between poor objective sleep and cardiometabolic health. (GH= Growth hormone, CVD= Cardiovascular disease, HTN= hypertension) Image taken from Knutson KL. Sleep duration and cardiometabolic risk: a review of the epidemiologic evidence. Best practice & research Clinical endocrinology & metabolism. 2010;24:731-743.

Tips to Improve Sleep

It is easy to recommend that a person must sleep between 7-9 hours for good health. However in reality, it is often difficult to implement it. The key challenges for a good sleep is often work pressure, consumption of caffeine and alcohol late in the night, excessive food consumption and use of technology close to bed time. Some of the simple tips that can be taken to improve sleep are

  • Maintain a cool sleeping environment. Research shows that maintaining room temperatures of 23-24 C helps one sleep better.
  • Do not use your mobile phones or laptops close to bed time. The blue light emitted by cell phones, laptops etc affect the production of melatonin , the sleep inducing hormone and thus affecting your sleep cycle.
  • Do not consume caffeinated products such as energy drinks, coffee, tea , aerated beverages close to bed time.
  • Avoid excessive calorie dense foods closer to bed time. Contrary to popular perceptions consuming carbohydrates during dinner will not make you fat. As long as you maintain calorie deficit , it is actually advisable to consume carbs in the evening. Carbs help in secretion of serotonin which induces sleep.
  • Avoid alcohol close to bed time.
  • Smoking is one of the strong contributing factors to sleep apnea and insomnia. Avoid smoking.

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