Persistent sleep disturbance may partially explain the dyspnoea often reported following hospitalisation with COVID-19 infection, according to a new study led by the Universities of Manchester and Leicester.
For the prospective cohort substudy, published in The Lancet Respiratory Medicine, researchers followed 1367 adult patients admitted to 83 hospitals across the UK and discharged between March 2020 and October 2021. The paper was also presented at the European Congress of Clinical Microbiology & Infectious Diseases in Copenhagen, from 15-18 April.
Data were collected at 2-7 months and 10-14 months after discharge, with sleep quality assessed subjectively via a questionnaire and numerical rating scale in 638 patients, and in another 729 patients by a wrist-worn accelerometer (actigraphy) for 14 days.
Participants were also clinically phenotyped at the earlier follow up visit, including assessment of anxiety, muscle function, dyspnoea, and lung function.
Sleep Quality Deteriorated After Discharge in Most Patients
A majority (62%) reported poor sleep quality in the questionnaire and a comparable proportion (53%) felt their sleep quality had deteriorated according to the numerical rating scale.
Actigraphy data showed that compared with a matched UK Biobank cohort who had recently been hospitalised, the post-COVID patients slept on average 65 min (95% CI 59-71) longer, had a lower sleep regularity index (-19%; 95% CI -20 to -16), and a lower sleep efficiency (3.83 percentage points; 95% CI 3.40 to 4.26). Similar results were obtained when comparisons were made with the non-hospitalised UK Biobank cohort.
In addition, decrements in sleep quality among the patients were associated with higher dyspnoea scores and impaired lung function, as assessed by forced vital capacity. Anxiety mediated 18-39% of the effects of sleep disturbance on dyspnoea, while muscle weakness mediated 27-41% of this effect.
Targeting Sleep Disturbance Could Have Clinical Benefit
The team acknowledged that sleep disturbance is in any case common following hospital admission, but suggested that targeting sleep problems might be beneficial in treating post-COVID-19 symptoms.
First author Callum Jackson, a mathematician at the University of Manchester, said: "Understanding the causes of breathlessness is complex, since it can arise from conditions that affect the respiratory, neurological, cardiovascular, and mental health systems.
"These same systems are also affected by sleep disturbance, another symptom that has been frequently reported after COVID-19."
Co-author Chris Brightling, clinical professor in respiratory medicine at the University of Leicester, said: "Future research should now assess whether interventions targeting sleep disturbance can improve not only sleep quality but also breathlessness through reducing anxiety and improving muscle strength."
Anxiety Could be Underlying Influence
Commenting to the Science Media Centre, David Ray, professor of endocrinology, Oxford Centre for Diabetes, Endocrinology, and Diabetes, and Sir Jules Thorn, from the Sleep and Circadian Neuroscience Institute at the University of Oxford, said: "Observational data can identify associations, and here breathlessness was associated with poor sleep. It could be that breathlessness leads to poor sleep, the other way around, or something else, e.g. anxiety could lead to both."
They added: "It is clear that poor sleep and poor quality of life are closely linked, and so attention to improving sleep may be a low risk, and high gain approach to help people suffering with long COVID. That would require a proper interventional trial, and that may be hard to do as the COVID waves are now subsiding."
Funding for the study was provided by UK Research and Innovation, the National Institute for Health Research, and the Engineering and Physical Sciences Research Council.