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Sleep And Immunity

Sleep and immunity. What is the correlation between them and how can you be healthier while sleeping?

What research says about adequate sleep and how it can improve our immune system.

There are several studies carried out in the most respected research centers around the world that support this assumption and that prove that there is a correlation between sleep and immunity. When we sleep, our body restores not only the energies spent throughout the day, but also the energy spent by our immune system when it fights diseases.

How can we be healthier while sleeping?

Our body needs energy to operate. Calories, proteins, vitamins and other substances are essential for our organism to build its defenses against external agents, be they viruses or bacteria.

It turns out that our immune system creates “defense cells” (such as T and B lymphocytes) and releases cytokines that have anti-inflammatory properties, attacking and destroying external agents like viruses. However, this process can often destroy the cells, which need to be replaced. 

The cell renewal process takes place precisely when we are sleeping, since it is during the least active period of our organism that the immune system can perform these functions more efficiently..

In addition, it is during sleep and its distinct phases that other events of great importance to our immunity occur:

✓ Production of hormones such as melatonin, or “sleep hormone”, which regulates our biological clock and GH, known as growth hormone;

✓ Metabolization of free radicals;

✓ Recomposition of cardiorespiratory functions;

✓ Restoration of tissues and increase in muscle mass;

It is when we sleep that the immune system “fixes the house” and immunity is restored so that we can face the next day with more disposition and health. And that is one of the reasons why rest periods are so important.

What happens to our immunity when we don’t sleep well?

When we don’t sleep well the production of antibodies is impaired and there is no replacement of cells that were used to fight the invasion of disease-causing viruses, so that they continue to replicate at a faster rate than the production of fighting agents, slowing down the healing process or even worsening symptoms.

In addition, according to information from the Sleep Institute of São Paulo, when we sleep for a period considered below ideal, the production of cortisol in our body increases, a hormone linked to stress that, in excess, decreases the defense reaction against foreign agents on the body.

There is more:

  • A study by the Instituto do Sono found that the production of antibodies drops by half in people who had vaccinated against hepatitis;
  • An article signed by the University of California, USA, indicated that the risk of getting a cold is 4.5 times higher in people who do not sleep at least five hours a day;
  • According to researchers at the Federal University of São Paulo (Unifesp), lack of sleep generates an inadequate immune response, leaving the body more susceptible to infectious diseases;
  • Unifesp researchers also point out that in addition to being vulnerable to colds and flu, sleep deprivation increases the incidence of different types of cancer, such as breast, lung and prostate cancer, as well as cardiovascular diseases.

The sleep deprivation period does not have to be long for the negative impact on immunity to happen.

Of course, long, consecutive bad nights as well as sleepless nights can be very harmful to our health. When it comes to our immune system, those who think that immunity problems arise only after long periods of insufficient sleep are in the wrong.

In fact, there are several studies that point out that just one night of poor sleep already has negative impacts on our immunity.

One of those studies, published by JAMA in 2002, found that the immune response of vaccines against the Influenza A virus fell by about 50% in volunteers who had only one night of sleep restriction, that is, their sleep time was reduced, in comparison to those with normal sleep conditions.

In addition, there are events in the sleep stages that can have a negative influence on sleep, not allowing the body to relax and the immune system to recover efficiently.

The causes of these events are diverse and from exams that assess sleep, such as actigraphy, it is possible to collect data that help identify what happens while you sleep.

What are the stages of sleep?

There are four stages: phase 1, 2, 3 and the fourth stage, called REM (Rapid Eye Movement). Each stage takes an average portion of the total sleep time during which events take place in our organism that aim at regulating the functioning of our body and fixing learning processes, for example.

STAGE 0110% of the night’s sleepTransition between wakefulness and sleep. The release of melatonin begins when it gets dark, inducing drowsiness. 
STAGE 0245% of the night’s sleepReduction of cardiac and respiratory rhythms, relaxation of muscles and reduction of temperature. It is the lightest sleep.Energy saving Restoration of tissues Increased muscle mass GH hormone release
STAGE 0325% of the night’s sleepReduction in metabolic rate; heartbeat is slower and breathing becomes lighter. 
REM20% of the night’s sleepDreams occur and the information of the day is processed. There is an adrenaline rush and spikes in heart rate and pressure (also caused by nightmares).Consolidation of memory and learning


As we have seen throughout this article, the cause of our colds and flu, which steal our energy and sour our mood, can be linked to the quality of sleep. But it is always good to remember that it is a cause and not the cause. The fact is that, with an immune system functioning fully, we can get rid of a series of diseases and be prepared for more severe illnesses.

This reinforces the importance of quality sleep for immunity as well as physical and mental well-being. So, if you have trouble sleeping, sleep too little, or feel tired after waking up, you should look for a doctor and pay special attention to it since a good night’s sleep is literally a way to solve a series of problems while sleeping.

See you next time.

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