Drinking to unwind after work may make firefighters’ sleep worse—and vice versa

A new study published in Nature and Science of Sleep reveals that alcohol use and poor sleep form a bidirectional, self-reinforcing cycle among firefighters—each making the other worse. The findings, drawn from objective sleep data collected from firefighters across four Pacific Northwest fire districts, offer some of the clearest evidence yet of how daily substance use shapes sleep health in this high-risk occupational group. 

Firefighters already face significant sleep disruption from irregular work schedules, overnight emergency calls, and high occupational stress. The study, part of the Shiftwork in Firefighters (SWIFT) study at the Oregon Institute of Occupational Health Sciences at Oregon Health and Science University, tracked 120 firefighters over up to three 14-day periods, collecting more than 2,600 observations on sleep, alcohol, nicotine and caffeine intake.

Key findings

Alcohol and sleep duration form a cycle. On days when firefighters drank more than their personal average, they woke up earlier and slept less the following night. But the relationship worked in both directions: nights of shorter or later sleep predicated up to 33% greater alcohol consumption the next day. The researchers suggest this may reflect impaired decision-making influenced by insufficient sleep—a pattern that could trap firefighters in a harmful cycle.

Caffeine was counterintuitive. Contrary to the research teams’ expectations, firefighters who consumed more caffeine tended to have slightly better sleep efficiency, fewer nighttime awakenings, and longer total sleep time. Although the researchers note that they only collected data on how much caffeine participants ingested throughout the day and not when, specifically, they ingested the caffeine.

The research team found that smokeless tobacco shortened sleep by about 30 minutes—a clinically meaningful difference consistent with the general population. The research team was unable to measure the impact of cigarette use due to an insufficient sample size of cigarette smokers in the study population.

“Alcohol, caffeine, and nicotine don’t operate in isolation—their effects on sleep are substance-specific and deeply intertwined with the daily rhythms and occupational culture of firefighters’ lives,” said study lead author David Reichenberger, Ph.D. “Understanding these dynamics is essential to designing targeted interventions that can genuinely improve sleep and reduce alcohol-related risks in this population.”

The authors note that interventions targeting healthier coping strategies for occupational stress and trauma could yield downstream benefits for both alcohol use and sleep health among firefighters.

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This study was supported by the Oregon Healthy Workforce Center, the National Institute for Occupational Safety and Health, and the National Institutes of Health.

Contact: David Reichenberger, Ph.D. reichenberger@ohsu.edu; Oregon Institute of Occupational Health Sciences, OHSU