Getting sleep in the fire service is difficult for many reasons: unpredictable alarm times disrupt falling asleep and staying asleep, while 24–48 hour shifts cut total sleep into fragmented, lower-quality periods. Even hypervigilance, a common job-related trait, can persist off-duty and disrupt sleep patterns. Firefighters are among the most sleep-deprived professionals in any workforce as shift structure, unpredictable call volume, and physiological stress responses combine to make quality rest difficult to achieve — and difficult to recover from.
The physiological arousal caused by tones—such as increased heart rate and cortisol release—can last for 30–60 minutes after a call. All these factors contribute to documented health consequences such as reduced cognitive sharpness and decision-making speed, elevated cardiovascular disease risk, hormonal dysregulation (cortisol, testosterone, insulin), increased systemic inflammation, higher rates of occupational injury, and greater susceptibility to mental health conditions, including PTSD and depression.
Compounding Effect: Exposure + Sleep Deprivation
The key takeaway for firefighters is the cumulative effect of exposures and sleep deprivation. Occupational smoke and chemical exposure are already known to cause cardiovascular and respiratory stress. Sleep deprivation independently damages those same systems. When both are experienced by firefighters, their combined physiological impact is greater than either factor alone.
Dark Mode Benefits
The dark adaptation problem. Firefighters working in low-light conditions depend on contrast sensitivity to differentiate objects from backgrounds — like spotting a squad member in a smoke-filled room or identifying a fallen obstacle. Dark adaptation increases sensitivity to both high and low light. But, looking at a bright computer or phone screen can cause “night vision blindness," making it difficult to see clearly in the dark after exposure to a bright screen. Healthy eyes take 10-30 minutes to adapt to darkness, and looking at a bright screen can reset this process.
Cognitive performance. For emergency responders, the dose-dependent relationship between shift work and poor health outcomes means that the longer someone works rotating shifts, the higher their risk becomes. Using dark mode can help reduce circadian disruption, which impairs cognition and reaction time, a small but meaningful safety factor.
Learn more about using the Dark Mode feature in IPSDI Exposure Tracker to support firefighters' health and safety.