Night shift workers who also 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 published in the Scandina a growing body of evidence linking circadian disruption to worse infectious disease outcomes and carry direct relevance for pharmacists and pharmacy staff, who oftentimes work rotating or overnight shifts.1,2
Study Design
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. Long COVID was defined as persistent symptoms lasting more than 3 months following a documented SARS-CoV-2 infection. Investigators used Poisson regression to evaluate both the independent and combined effects of night shift work and sleep disturbances, including chronic insomnia, stratifying results by sex, body mass index, and chronotype.1
Key Findings
Among 1899 participants who were newly infected with SARS-CoV-2 during follow-up, 284 (15%) reported long-COVID symptoms. Compared with day workers, night shift workers had an 88% higher risk of developing long COVID (95% CI, 1.29-2.72), a risk that increased further among night workers with obesity
Chronic insomnia in the general population was independently associated with a 42% higher risk (95% CI, 1.12-1.78). The combination was particularly striking, as night workers with chronic insomnia had 2.7 times the risk of long COVID compared with day workers without insomnia (95% CI, 1.60-4.51). Associations held up across multiple sensitivity analyses, reinforcing the robustness of the findings.1
Biological Plausibility
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 in the <a href="https://healthylife7.com/why-the-same-virus-can-be-mild-for-some-and-deadly-for-others/” title=”Why the same virus can be mild for some and deadly for others”>same journal, which pooled data from 14 studies involving more than 191,000 workers and found that night shift work was associated with a significantly elevated risk of SARS-CoV-2 infection (OR, 1.31; 95% CI, 1.09-1.58), even though evidence for common respiratory infections like influenza and the common cold was less consistent. The 2 studies suggest the sleep and circadian pathway may affect not just the likelihood of infection but also how completely the body recovers from it.1,3
Context Within the Long-COVID Burden
CDC surveillance data show that long COVID prevalence among US adults who have ever had COVID-19 has remained in a persistently elevated range in recent years, with significant activity limitations reported by roughly 1 in 5 of those affected. Identifying modifiable occupational risk factors, such as shift scheduling and sleep hygiene, could meaningfully inform prevention strategies as the condition continues to affect workforce productivity and quality of life nationally.4
Implications for Pharmacy Practice
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. A 2024 study in BMC Health Services Research found that pharmacists working irregular hours or night shifts commonly report poor sleep quality, which has separately been linked to compromised immune function and increased risk of clinical errors. That study’s authors called for workplace interventions such as flexible scheduling and adequate rest periods between shifts to protect pharmacist health.5
Looking Ahead
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
Pharmacists counseling shift-working patients, or managing their own schedules, may want to treat sleep quality as a modifiable risk factor worth addressing proactively, not just for daytime alertness, but potentially for long-term post-infection recovery
