Poor sleep increases the severity of viral respiratory infections including COVID-19
Poor sleep increases the severity of viral respiratory infections including COVID-19

Poor sleep increases the severity of viral respiratory infections including COVID-19

A new study sent to the preprint server medRxiv * explores the risk of respiratory infection with poor sleep in connection with the ongoing coronavirus disease 2019 (COVID-19) pandemic.

Examination: Impact of public health on poor sleep on severe COVID19, influenza and upper respiratory tract infections. Image credit: SB Arts Media / Shutterstock.com


Previous studies have shown that poor sleep is associated with many different conditions, including inflammation and viral infections. With the acute loss of sleep, the level of circulating cytokines such as interleukin-6 (IL-6) and C-reactive protein (CRP) increases. Vaccine responses can also be delayed by insomnia; however, this may be a transient effect.

Chronic sleep loss has been associated with more serious effects, including higher death rates from all causes and viral infections, as well as up to a 30% increased risk of respiratory infections. These effects of sleep loss may be due to chronic inflammation induced by prolonged insomnia, leading to a lower immune response and consequently increased severity of infections.

During the COVID-19 pandemic, several reports have suggested that some people experienced even less sleep, had nightmares and changes in their body rhythms as a result of quarantines, changed life and work routines, and higher stress levels. Post-COVID comorbidities are also associated with poor sleep.

Some researchers suggested that shift work disrupts daily rhythms of sleep and activity, as well as metabolic rhythms, causing an increased susceptibility to COVID-19. The current study focuses on the causal link between sleep and respiratory infections.

Survey results

In two large population-based cohorts, a diagnosis of insomnia was associated with a significantly increased risk of either influenza or upper respiratory tract infection (URI). These results come from a follow-up of over 25 years and should therefore not be rejected.

In the FinnGen group, the risk of developing a URI or influenza was almost three and five times higher, respectively, after an earlier diagnosis of insomnia. However, the incidence of COVID-19 was not significantly increased. With data from the UK Biobank, the risk of URIs and flu was increased by about half after a diagnosis of insomnia.

The significant discrepancy in risk increase between the two studies may be due to the difference in the way the records were maintained. With FinnGen, only hospital records were used, which implies more severe cases of insomnia. In contrast, UK Biobank data included both primary care and hospital diagnoses.

The Mendelian randomization analysis (MRI) is a form of genetic epidemiology used to provide information about how a given exposure is causally related to an outcome through genetic variants that are already known to be associated with the exposure. Using this valuable tool, the researchers in the current study found a strong causal relationship between the risk of influenza, URI and COVID-19 hospitalization and the severity, as well as a small increase in the risk of becoming infected with the severe acute respiratory syndrome coronavirus 2 (SARS). CoV-2).

Insomnia turned out to be a risk factor for severe Symptoms of covid-19, with a 64% increase in risk and an approximately 50% greater risk of hospitalization due to COVID-19. A history of insomnia also increased the risk of influenza and URI by about 70% each. However, some confusing factors may also contribute to the severity of COVID-19 and hospitalization and were not evaluated by the analysis.

Usually sleeping less than six hours a night was also a risk factor for COVID-19, but not for hospitalization risk, flu or URI. The current study was underpowered, meaning that only a doubling of the risk of severe COVID-19 or a 60% increase in COVID-19 hospitalization risk could have been detected with these figures.

Similarly, increases in the risk of COVID-19, influenza and URIs of more than 25%, 135% and 57%, respectively, can be detected. Thus, there may be a significant correlation that needs to be further analyzed in studies that are adequately powered to these results.


The results of the current study are similar to previous reports, suggesting that sleep affects immune function and as a result reduces the antiviral response and promotes more severe infection. Some of the observed changes in this study that occurred as a result of sleep deprivation included increased levels of inflammatory chemicals and markers.

As opposed to simply observing associations between sleep disorders and respiratory infections, which could be two-way, the current study showed that chronic insomnia is actually a contributing cause of infections. However, the strongest degree of association was with severe COVID-19 rather than with SARS-CoV-2 infection, despite the fact that the study was driven to the latter.

The researchers attributed this observation to the modulating effect of sleep by increasing the severity of the infection instead of causing infection. In particular, other factors associated with the respiratory tract infection, including body mass index, obstructive sleep apnea, and hyperglycemia, were also not considered in the current study. This is consistent with the increased levels of inflammatory markers in severe COVID-19 patients, rather than those experiencing mild COVID-19.

Second, insomnia and COVID-19 incidence / severity increase in poor population groups, certain ethnic groups, specific occupations and with age, as well as in men. Thus, the uneven distribution of these factors could reflect the increased severity of infection in this group.

Finally, the factors that affect insomnia can also in themselves affect the risk of respiratory infection. Since low blood oxygen levels and short sleep duration are potential risk factors for inflammation, which are also associated with insomnia and obstructive sleep apnea, these factors may also have separate biological effects that increase the risk of respiratory infections.

These results highlight the role of sleep in maintaining an adequate immune response to pathogens. As the current COVID-19 pandemic has increased the number of people suffering from poor sleep, safe interventions such as sleep management and treatment of insomnia can reduce infections and save lives. “

*Important message

medRxiv publishes preliminary scientific reports that are not peer-reviewed and therefore should not be considered essential, guide clinical practice / health-related behavior or be treated as established information.

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