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A large new study suggests that when U.S. veterans experience a shift from normal to abnormal levels of daytime sleepiness, their risk of dying within five years increases significantly—particularly if they are over 55. The findings come from a retrospective analysis of nearly thousands of veterans enrolled in the Veterans Health Administration system and tracked for changes in their self-reported sleepiness over time. The research, published in the Journal of Sleep Research, provides evidence that worsening daytime sleepiness may serve as an early warning sign of underlying health risks.
Excessive daytime sleepiness is a common issue that can interfere with alertness, performance, and quality of life. It becomes more prevalent with age and has been linked to cardiovascular problems, mental health conditions, obesity, and even early death. The veteran population is especially vulnerable to sleep disturbances due to factors such as post-traumatic stress, traumatic brain injuries, and other service-related conditions. Recognizing this, the Department of Veterans Affairs has made sleep health a priority, incorporating regular assessments like the Epworth Sleepiness Scale into clinical care.
The Epworth Sleepiness Scale is a widely used, self-reported questionnaire that asks individuals to rate their likelihood of dozing off in everyday situations. Scores range from 0 to 24, with scores of 11 or higher indicating abnormal sleepiness. While previous research has found that high scores are associated with increased mortality, most studies have only looked at a single snapshot in time. The team behind this study wanted to examine whether changes in sleepiness over time might offer even more insight into future health risks.
“Veterans experience higher rates of sleep problems than the general population, which can contribute to serious health issues,” explained study author Katherine G. Bay of the Center for Innovations In Quality, Effectiveness, and Safety at the Michael E. DeBakey VA Medical Center.
“The Epworth Sleepiness Scale is a validated tool for measuring excessive daytime sleepiness and has been collected in VA clinics for decades, but until recently, this data could not be analyzed at scale. With the advent of new natural language processing tools, we saw an opportunity to finally extract this large amount of data to study these patterns over time. We felt it was important to understand how changes in daytime sleepiness might predict health risks, including mortality, in veterans.”
The research team analyzed medical records from the Veterans Health Administration between October 1999 and August 2018. They focused on 17,967 veterans who had two Epworth Sleepiness Scale scores recorded at least three months and no more than five years apart. To retrieve these scores from unstructured clinical notes, the researchers used a natural language processing system that had been validated to extract the data with 96 percent accuracy.
Participants were categorized into four groups based on how their scores changed between visits: those who remained in the normal range (Normal-Normal), those who moved from normal to abnormal (Normal-Abnormal), those who remained in the abnormal range (Abnormal-Abnormal), and those who improved from abnormal to normal (Abnormal-Normal). The researchers then tracked whether each participant died within five years of their second recorded sleepiness score.
After adjusting for variables such as age, sex, race, and existing medical conditions, the results showed that veterans who shifted from normal to abnormal sleepiness scores had a 25 percent higher risk of dying within five years compared to those who remained in the normal range. This increased risk was most apparent in veterans aged 55 and older, whose risk was nearly 50 percent higher than peers who did not experience worsening sleepiness.
In contrast, those who had persistently high sleepiness scores or who improved from abnormal to normal did not show significantly different mortality rates compared to the consistently normal group. This finding suggests that a sudden or progressive onset of excessive sleepiness, rather than a persistent condition, may be more indicative of declining health.
Additional analyses showed that certain subgroups were more likely to experience worsening sleepiness. For example, individuals who developed chronic pulmonary disease or whose body mass index increased to 35 or above had higher odds of shifting from normal to abnormal sleepiness scores. However, other conditions such as diabetes or cardiovascular disease did not show a significant association in this particular study.
“We expected multiple comorbid conditions to track with new daytime sleepiness, but only significant weight gain and new diagnoses of chronic pulmonary disease stood out,” Bay told PsyPost. “While these findings don’t prove causation, they give us important leads for future work, especially for understanding which veterans might be most vulnerable.”
Importantly, the predictive pattern held regardless of whether the time between the two exams was short or as long as five years. This consistency suggests that tracking sleepiness changes—even over shorter periods—may provide meaningful information about long-term health risks.
“It’s all about monitoring change: These findings suggest that new onset daytime sleepiness could be an early warning sign worth a provider’s attention, especially since the ESS is quick, inexpensive, and already used in VA sleep clinics,” Bay said. “Veterans who developed new symptoms of excessive daytime sleepiness had a 25% higher likelihood of dying within the next five years, even after accounting for age, comorbidities, and other risk factors. In contrast, those with consistently high or improving sleepiness scores did not face the same increased risk.”
While the study provides evidence of a link between worsening daytime sleepiness and increased mortality, it has some limitations. The sample included only veterans who were healthy enough to attend two sleep clinic visits within the Veterans Health Administration system, which may not reflect the broader population. Veterans receiving VA care also tend to be older, have more health problems, and come from lower socioeconomic backgrounds than those receiving care elsewhere.
The study also relied on self-reported measures of sleepiness, which can be affected by individual differences in awareness and reporting accuracy. The Epworth Sleepiness Scale, while widely used, may not capture all dimensions of sleep-related dysfunction. Additionally, data on smoking history were largely missing, and specific causes of death were not available. The researchers also lacked information on whether treatments administered after the first sleepiness score contributed to any changes in mortality risk.
“Because this study was limited to veterans who sought sleep care in VA clinics, we can’t assume the same results apply to the broader population,” Bay noted.
Still, the study represents one of the largest and most detailed analyses of how changes in subjective sleepiness relate to survival, particularly in a medically complex population, and the researchers plan to build on this work.
“Our next step is to determine whether there’s a specific threshold or change in ESS scores that should trigger concern from providers,” Bay explained. “We also want to explore which medical conditions or treatments may be associated with these changes, with the goal of identifying strategies to reduce risk in Veterans who develop new sleepiness symptoms.
The study, “Changes in Self-Reported Excessive Daytime Sleepiness Are Associated With 5-Year All-Cause Mortality Risk Among Veterans,” was authored by Katherine G. Bay, Arash Maghsoudi, Amin Ramezani, Drew A. Helmer, Amir Sharafkhaneh, and Javad Razjouyan.
