Night Shifts Nearly Double Long Covid Risk, Vienna-Led Study Finds

Vienna and ISGlobal research links night work to an 88% higher Long Covid risk, with insomnia adding 42% and combined risks nearing 2.7 times.

Employees who work through the night face a substantially greater chance of developing lasting health problems after a coronavirus infection, according to research from the Medical University of Vienna and the Barcelona-based research institute ISGlobal. Their findings appear in the Scandinavian Journal of Work, Environment & Health.

The study compared shift workers with people who work only daytime hours and found that the former group reported persistent symptoms far more often following infection.

What the numbers show

Night work carried an 88 percent higher risk of Long Covid than daytime-only work. Even a schedule of at least three night shifts per month was linked to a risk slightly more than double that of day work.

Sleep problems emerged as a separate danger in their own right. Chronic insomnia raised Long Covid risk by 42 percent regardless of shift patterns. When both factors were present — night work plus poor sleep — the odds of lingering symptoms climbed to nearly 2.7 times the baseline.

Among participants who did develop Long Covid, 54 percent experienced neurological symptoms.

Where the data came from

The researchers drew on 1,899 participants in Spain's COVICAT cohort, tracked between 2021 and 2023. Roughly 280 of them — about 15 percent — went on to develop Long Covid, which the team defined as health complaints persisting more than three months after the acute infection.

One detail stood out: night work did not appear to raise the likelihood of catching the virus in the first place. The gap between the groups showed up not at the point of infection but in how the illness unfolded afterward.

Reading the results with care

This is an observational study, which means the data can establish a statistical link between night shifts, sleep deficits and prolonged Covid symptoms but cannot prove a direct cause-and-effect mechanism.

Even so, the results offer practical leads for workplace health protection and occupational medicine. Because shift work and sleep disorders are common across many industrial and service sectors, the research underlines why ergonomically designed shift schedules and targeted sleep-health measures on the job deserve attention.