Today's busy life, the habit of staring at the screen till late night and heavy work pressure have badly disturbed the sleep patterns of people. Most people think that sleeping less than six hours will only make them feel a little lazy or have a headache throughout the day, but the reality is much more serious and life-threatening. Global health research and medical science studies make it clear that when you do not get enough sleep, your body starts losing its natural ability to fight against infections, viruses and seasonal diseases i.e. immune system. Sleep is not just a means of resting, but it is also a time when the body repairs itself and recharges disease-fighting defense mechanisms. The biological relationship between sleep and the immune system: what happens inside the body? When we are in deep sleep, our body is not only lying dormant, but during that time the immune system becomes active and produces and secretes special proteins, which are called 'Cytokines'. Certain types of cytokines play an important role in fighting infection, inflammation, and mental or physical stress in the body. When the body is attacked by a virus or bacteria, the immune system requires large amounts of these cytokines. If a person is suffering from continuous sleep deprivation, the production of protective cytokines in his body decreases rapidly. Apart from this, the activity of the main infection-fighting white blood cells called 'T-cells' and their adhesion capacity at the sites of infection also weakens. The result is that the primary defense system that destroys germs that enter the body slows down. Shocking revelations of scientific research: From cold and flu to the effect of vaccines, it has been proved in many prestigious studies conducted on sleep and immunity that people who sleep less than 6 hours at night are 4 times more likely to be affected by common cold or flu virus than those who get complete sleep for 7 to 8 hours. When the body is tired, viruses easily multiply in the respiratory tract. Not only this, less sleep also has a direct impact on the effectiveness of vaccination. Researchers have found that if a person does not get enough sleep after getting vaccinated against hepatitis, flu or any other disease, his body is not able to develop enough antibodies against the vaccine. This means that despite being vaccinated, the person's protective shield remains incomplete. Lack of sleep increases the risk of cortisol and chronic inflammation. Incomplete sleep not only increases the risk of external infections, but also disturbs the internal system of the body. If one does not get enough rest, the body starts secreting more of the stress hormone i.e. 'Cortisol'. Chronically high levels of cortisol suppress the activity of immune cells present in the body, which is medically called 'immunosuppression'. Additionally, prolonged sleep deprivation increases 'systemic low-grade inflammation' in the body. This hidden internal inflammation gradually damages the blood vessels and further increases the risk of type-2 diabetes, high blood pressure, heart attack, stroke and autoimmune diseases manifold. When the immune system is under stress around the clock without resetting, it starts attacking its own healthy tissues. How much sleep does the body require as per age? National and international health organizations (such as WHO and National Sleep Foundation) have different sleep requirements for each age group: Infants and toddlers (0-5 years): 11 to 14 hours (including daytime naps) School-age children and teens (6-17 years): 9 to 11 hours Adults (18-64 years): 7 to 9 hours of uninterrupted sleep Senior citizens (above 65 years): 7 to 8 hours Experts say only bed But the time of lying down does not matter, rather the quality of sleep is equally important. It is during deep sleep and REM sleep that the most active production of repair hormones and antibodies occurs in the body. Follow the rules of 'Sleep Hygiene' for deep sleep and strong immunity. If you want to keep your immunity naturally strong, then before taking medicines, you will have to improve your sleeping habits: Sleeping and waking up at a fixed time: Fix the same time to sleep every night and wake up in the morning. Do not change this routine too much even on weekends so that the body's internal circadian rhythm remains balanced. Distance from the screen 1 hour before sleeping: Blue light emitted from mobile, laptop and TV screens stops the secretion of 'melatonin' (sleep-inducing hormone). Study a book or listen to calming music before going to sleep. Avoiding caffeine and heavy food: Avoid coffee, tea, nicotine and excessively sweet things after 5 pm. Keep dinner light and eat at least 2 to 3 hours before sleeping. Bedroom environment: Keep the room temperature cool, turn off lights completely and create a noise-free environment. Daytime sunlight and physical activity: Get exposure to natural sunlight for at least 20-30 minutes a day and do regular light exercise. This gives the body deep and comfortable sleep at night.