Night shift workers who experience chronic insomnia face nearly 3 times the risk of developing long COVID compared with day workers who sleep well, according to a new population-based cohort study.
The study, published in the Scandinavian Journal of Work, Environment & Health, found that night shift workers had an 88% higher risk of developing long COVID, a risk that increased further among night workers with obesity.
Researchers followed participants in the COVICAT study, a population-based cohort of adults in Catalonia, Spain, assessing night shift work and sleep characteristics in 2021 and tracking outcomes through 2023.
Among 1899 participants who were newly infected with SARS-CoV-2 during follow-up, 284 reported long-COVID symptoms.
Chronic insomnia in the general population was independently associated with a 42% higher risk of long COVID.
The combination of night shift work and chronic insomnia was particularly striking, as night workers with chronic insomnia had 2.7 times the risk of long COVID compared with day workers without insomnia.
The authors note that circadian and sleep disruption may heighten susceptibility to, and severity of, SARS-CoV-2 infection through proposed mechanisms, including dysregulated immune signaling and impaired inflammatory resolution during sleep loss.
These findings align with a 2025 systematic review and meta-analysis, which found that night shift work was associated with a significantly raised risk of SARS-CoV-2 infection.
CDC surveillance data show that long COVID prevalence among US adults who have ever had COVID-19 has remained in a persistently raised range in recent years.
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Significant activity limitations are reported by roughly 1 in 5 of those affected.
Identifying modifiable occupational risk factors, such as shift scheduling and sleep hygiene, could inform prevention strategies as the condition continues to affect workforce productivity and quality of life nationally.
This could be an important consideration for pharmacists counseling shift-working patients, or managing their own pharmacy operations.
Pharmacists are frequently on the front line of counseling patients, including shift workers in health care, manufacturing, retail, and transportation, about respiratory illness prevention, vaccination, and sleep health.
These findings offer another evidence-based talking point for at-risk patients.
Pharmacists themselves are not immune to the exposure, and a 2024 study found that pharmacists working irregular hours or night shifts commonly report poor sleep quality, which has been linked to compromised immune function and increased risk of clinical errors.
The study authors emphasize that their findings come from a large, prospective cohort with consistent results across sensitivity analyses, strengthening confidence in the association.
However, they also note that the underlying mechanisms connecting circadian disruption to long-COVID pathophysiology require further investigation.
