Little do we know it, but while we sleep our immune system is coordinating a busy night crew that is working hard to protect us from invaders and cleaning out the trash from daytime activity.

It is functioning as the nighttime security staff and maintenance personnel.

Research findings show that sufficient sleep is associated with reduced infection risk and can improve infection outcomes.

One study showed that short sleep was highly correlated with the likelihood of catching a cold - and was more predictive than any other factor, including age, stress, race, education, income - and even smoking. 

Understanding the immune system and sleep

The intelligence of the immune system is astonishing.

When it is operating properly, it keeps harmful invaders out of the body, and it responds to any breaches of defense (like an infection that has penetrated the body through the respiratory system) with a fast-acting coordinated response.

It is also constantly patrolling through the bloodstream and organs to find and destroy old, dead, or cancerous cells and anything else that needs to be eliminated and exited from the body. This is all going on 24-7.

Sleep supports the immune system in a number ways.

During sleep the immune maintenance crew comes out to sweep the brain and other organs of harmful debris, which need to get cleared out to maintain daytime efficiency.

While we sleep the immunological communication system is also hard at work, with special communication molecules call cytokines at a peak, busy transferring information throughout the body on how to best respond to any threats presenting themselves.  

Most of the time it is humming along doing its thing and we hardly notice. Its when we get an infection of some kind that we feel the effects and realize that our immune system is at work. 

During sleep, the immune system is also enhancing its memory. 

To make sense of that statement, we need to look a little deeper into what is going on in the immune system. 

Immunological response

We actually have two immune systems. One was inherited when we were born, called the innate immune system. The other is developed over our lifetime and it is called the adaptive immune system. The adaptive immune system responds to threats we encounter over the course of our lives and develops a memory to better respond to these threats. 

When a threat is encountered, special immune cells are created and multiply to overcome that threat. 

First, the threat is detected. Specialized cells detect the threat. Named “B-cells”, these identify the invaders and then create molecules (called antibodies) which attach to the invader.  When an antibody attaches to the cell of an invader, it is marked for death. 

Next, the threat is eliminated. Antibodies signal other cells (killer T-cells, natural killer cells and phagocytes) to attack and destroy the invader. 

Meanwhile, more recruits are being deployed. The communication system works full-tilt, the blood stream flooded with cytokines, carrying instructions for what is needed. 

Immunological memory

Once the threat is succumbed, information is stored for next time that same invader arrives. This information is carried through antibodies which had been created to identify the threat.

The body keeps a small supply of these antibodies. If that same threat is encountered again, a fast response is possible because the antibodies are already available and can be quickly replicated.

When a new threat attacks, one the body has never encountered before, the immune system must identify the threat and create new antibodies.

This can take a some time because the immune system is basically learning about the threat and meanwhile the infection is proliferating. By the time the body has created its antibodies, the infection is much harder to overcome. 

Stored antibodies provide a library of information, the body’s database for dealing with threats. (This is how a vaccine works, presenting a weaker form of a disease so the immune system can create antibodies and then quickly defend itself if necessary).

The body doesn’t have to learn again from scratch and is able to quickly mount a defense against any of these same attacks. We carry thousands and thousands of antibodies ready to replicated. 

This is the immunological memory.  

The immune response during sleep

The adaptive immune response functions during both sleep and wakefulness. However, the system shifts in emphasis of complementary functions during these two different states. 

During sleep there are more immune system cells at large that are “undifferentiated”.

These cells are ready to respond to new threats, to basically learn about the threat and recruit more cells to develop antibodies to it.

Communication molecules (cytokines) specifically transfer this information throughout the body, helping the body mount a defense. Consider them the “night patrol” of the body.  It is thought that sleep enhances the consolidation of immunological memory for any specific type of invader or threat. 

Sleep enhances the efficiency and efficacy of the adaptive immune response system.

This happens through threat detection, elimination, mounting a heightened response, and consolidating immunological memory.

Here is an analogy to picture the difference good sleep can make for a strong immune system:

Imagine that you wake up at night to the smell of smoke in your house and you suspect a fire. Picture the different outcomes if you call 911 and an emergency response team arrives at your door within minutes …. Compared to what would happen if for some reason there were no trained firefighters available and you had to rouse your neighbors to come and help you fight the fire. Good sleep can make the difference between getting the professional firefighters vs coordinating your neighbors to fight a fire. 

What you can do to support your immune system

Four complimentary functions support our immune system to perform at its best: sleep, healthy diet, moderate cardiovascular exercise and keeping stress at bay.

Get good sleep

Your sleep system responds well to routine; get up a the same each morning and go to bed at the same time at night (ideally within a 30 minute window of time).

Light has a huge impact on your sleep; go outside and get some daylight in the morning; avoid blue screens at night.

Prepare your body for sleep; Establish a 30 minute wind-down routine. Do something relaxing, as long as this does not involve screen time.

Download our free guide at the end of this post!

Eat a well-balanced diet

To enhance your immune system, eat lots of fresh fruit and vegetables. These provide vitamins, minerals and phytonutrients your immune system needs to function at its best. Phytonutrients are the chemicals in fruit and vegetables that give them color - and which your body recruits to maintain health. 

Get physical exercise

Exercise enhances immune function. Moderate cardio exercise is most recommended  - your heart rate should be elevated a bit from the exertion. Suggestions for moderate exercise include walking, walking up stairs, gardening and working around the house - things that get you moving. For more intense exercise, jogging, cycling or skipping are good alternatives. If you haven’t exercised in a while, stick with low-intensity activities like walking.

Manage stress

Chronic stress suppresses the immune system. This is because stress hormones interfere with the immune response. We are adapted to be able to deal with acute stress - a short sharp shock that quickly dissipates.

During an emergency, we need to recruit focused resources.

When stress is an ongoing, a daily grind wearing down body and mind, that the immune system suffers.