Home » Sleep and Immune system: Why do we need sleep?

Sleep and Immune system: Why do we need sleep?

by Aaima Ayub
sleep and the immune system

Sleep and the immune system are closely related. Even the smallest of alterations in the sleep cycle has adverse effects on our health. We become lazy, drowsy, irritated, and experience various physical and mental issues. When we sleep during the night, our body gets busy. It gets time to correct any problems. Moreover, at certain hours of the night, our immune system also becomes very active.

An average human spends 26 years of his precious life doing absolutely nothing i.e Sleep. It is impossible to avoid sleep. Randy Gardner was the only person who manages to stay awake for 11 days and 25 minutes, creating a world record in 1964. So why is it that we need to sleep? The answer is simple. We get sick if we don’t.

“Death, so-called, is a thing which makes men weep. And yet a third of life is passed in sleep”,

Lord Byron.


Sleep is not a single phenomenon. It has many stages, each of which is important in its way, establishing the relation between proper sleep and the immune system. The Stages are 1 2 3 4 and REM. In stage 1, we fall into a light sleep. Waking up from here is very easy. After that, we fall into stage 2 where our eyes stop moving and brain waves become slow. In stage 3 (slow-wave sleep) and 4, we finally fall into a deep sleep. There is no eye movement yet.  It is very hard to wake up from this (so it’s not our fault we miss our alarms, it’s all because of mother nature). Finally, we enter into the last stage, which is called REM, where we experience Rapid Eye Movement.

Most of the magic occurs in the Slow-wave sleep (SWS, 3rd stage) and REM stage. Here, sleep and the immune system join hands to defend our body through the night.


It is not a coincidence that sleep and the immune system have become so interconnected. Even while we are just lying down, a lot of action is going inside our system. Some researchers believe that this process is related to humans living in ancient times. Old humans did not have the luxury of houses and beds.

They roamed in wild and slept in open. There were many chances of contracting infections during the night. So maybe the alert immune system prepared them to counter any pathogen that infected them. Another theory is that during the night, our body defences get prepared for any danger in the following day. In a way, evolution perfected this phenomenon throughout centuries!


Sleep and Immune system

Cytokines are the chemical messengers of our immune system. Just as we use Watsapp to send messages to our friends, immune cells use cytokines to send signals to other cells. The type of cytokine depends on the message. Cytokine level changes when our body gets prepared to counter a threat.

The cytokines which are awake during the night are mainly IL6 (interleukin 6), IL2 (interleukin 2), IL12 (interleukin 12), interferons, TNF (tumour necrosis factor) and IL10 (interleukin 10). Furthermore, some receptors on cells (molecules that receive a signal) like TLR-4(toll-like receptor) and interleukin 6 receptors are also expressed.


I cannot emphasize enough how important it is to get adequate sleep during the night-time. Nocturnal sleep (sleeping during the night) and circadian cycle (our natural body clock) are the essences of the bond between sleep and the immune system. It is vital to maintain the ratio of sleep stages, when we are in slow wave speed and when we enter the REM stage. Also, the cytokines are extremely punctual.

Monocytes (immune cells) secrete IL6. These levels rise at 7pm in the evening and 5 am in the morning. IL6 then travels through blood and bind at its appropriate receptor where required. There may be some cells which do not have IL6 receptor. In that case, immune cells produce some soluble IL6 receptors which bind to IL6. This molecule now gives message to the cells which might not have any means to receive the signal like the neurons.

Some anti-viral movements also commence in our body when we are sleeping. Many types of white blood cells redistribute in our immune organs like soldiers in battlefield. White blood cells release IL2, IL12 and IFN-gamma which in turn wake up the T helper 1 cells. They also reduce the IL10 production as IL10 suppress the inflammatory process. All in all, sleep and immune system are very interconnected.



IN ancient times, monsters used to keep humans up at night. In this age, it is the social problems which have disturbed peace of mind. People develop insomnia  very commonly due to stress, anxiety and depression. This contributes to many other problems like irritability, loss of appetite and even infections by pathogens. All this just proves importance of proper sleep for immune system to work.

Sleep disturbance can rattle the ratio of sleep stages. This can be dangerous. Each stage is associated with a specific immune process. IL6 levels decrease so now we are less defenced against any infection. The cytokines which are supposed to be released at night start being secreted during the day. The body clock becomes a mess. Continuous lack of proper sleep causes us to go into a state of inflammation which is unnecessary and not very ordered.

Researchers concluded after a study on 50 000 people that IL6 and C reactive protein ( proteins of immune system) was increased. Another study involving 3000 people with African-American and white adults also showed how not having enough sleep can make us weak.


The individuals who were not sleeping enough were more at risk of common cold and pneumonia. This was proved by a study on 23 000 adults.


Not having proper rest could also cause faulty vaccine response. Meaning that body receives the vaccine but the vaccine does not work properly, all because of improper sleep. The vaccine response tested on people were against influenza virus, hepatitis A virus, hepatitis B virus, swine flu, and chicken pox virus. The people were still at risk of developing these infections.


ADEQUATE SLEEP IS IMPORTANT. Sleep and the immune system work together to prep our body’s defenses through the night. If we do not sleep properly, our immune system becomes disorderly. All of which eventually makes us weak and more susceptible to diseases. So to stay healthy, sleeping at the right time is vital.

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