Why Do Treated Sleep Apnea Patients Still Feel Sleepy? Work May Be the Missing Clue

For millions of people with obstructive sleep apnea, the promise of treatment is simple: keep the airway open at night, and the daytime fog will lift. Positive airway pressure therapy, known as PAP, does exactly that for most patients, splinting the upper airway with a gentle stream of pressurized air and eliminating the repeated breathing pauses that fragment sleep. Yet a stubborn minority of patients continue to battle overwhelming daytime sleepiness even after their apnea is objectively well controlled. This phenomenon, called residual excessive daytime sleepiness or residual EDS, has long puzzled sleep physicians, and a new letter published in the Journal of Clinical Sleep Medicine argues that the answer may be hiding in plain sight, in the workplace itself.

The letter, written by Christoph G.U. Riese and Ulrich Koehler of the Sleep Medicine Center at Philipps-Universität Marburg in Germany, responds to a larger investigation known as the MAGNETO study. That study, led by Junco and colleagues, made an unsettling discovery: patients with treated sleep apnea who still reported excessive daytime sleepiness also showed measurable cognitive deficits, including impairments in attention and psychomotor vigilance, the capacity to react quickly and consistently to incoming signals. Even after the researchers statistically adjusted for sex, the delay between symptom onset and diagnosis, and total sleep duration, the cognitive gap between sleepy and non-sleepy patients persisted. Something else, the MAGNETO team concluded, must be driving both the lingering sleepiness and the cognitive toll that accompanies it.

Riese and Koehler believe they may have identified at least part of that missing something. Their hypothesis grew out of a detailed analysis of 543 patients with obstructive sleep apnea who had not yet begun any treatment. When the researchers split the cohort by employment status, a striking pattern emerged. Patients who held jobs scored significantly higher on the Epworth Sleepiness Scale, the most widely used questionnaire for measuring daytime sleep propensity, with a mean score of 11.4 compared with 9.7 in non-employed patients, a difference that reached statistical significance. Crucially, this was not because the employed patients had worse breathing disturbances. The apnea-hypopnea index, which counts the number of breathing interruptions per hour of sleep, was essentially identical between the two groups, at 37.8 versus 39.1 events per hour.

The real difference lay in how much time the employed patients actually had available for rest. Weekly rest time, the window between the end of work and the start of the next working day, was 68 minutes shorter in employed patients, averaging 443 minutes compared with 511 minutes in their non-employed counterparts. Accumulated across the week, this translated into a cumulative sleep debt of 82 minutes for working patients versus just 13 minutes for those not employed. In other words, two patients with the same severity of sleep apnea could arrive at the sleep clinic with very different sleep budgets simply because one of them had a job that consumed more of the hours available for recovery.

These findings echo data from a much larger European effort. The European Sleep Apnea Database, a multicenter registry of patients across the continent, previously reported that roughly 28 percent of patients with obstructive sleep apnea continue to experience excessive daytime sleepiness despite adequate continuous positive airway pressure therapy. That analysis attributed the residual sleepiness to a mixture of cultural and lifestyle factors rather than to treatment failure alone. The Marburg cohort now adds a concrete, quantifiable dimension to that interpretation: employment itself, through the mechanism of reduced rest time and accumulated sleep debt, appears to be one of those lifestyle factors with a measurable physiological footprint.

But the German authors argue that the pathway from employment to sleepiness involves more than simple arithmetic of lost hours. Drawing on the occupational health psychology literature, they point to a meta-analysis of 201 studies showing that people who experience a strong sense of calling in their work tend to work longer hours and, more importantly, achieve poorer psychological detachment, the mental ability to switch off from job demands during leisure time. A related study of high-commitment workers found that difficulty hanging up, both literally and figuratively, was linked to worse sleep quality and reduced morning vigor, independent of how many hours were actually slept. Psychological detachment, in other words, is a quality of recovery that a stopwatch cannot fully capture.

This distinction matters because the brain treats incomplete recovery as a form of sleep loss even when time in bed seems adequate. Decades of experimental work, including a widely cited meta-analysis by Lim and Dinges, have demonstrated that even short-term sleep restriction produces reliable impairments in attention, working memory, and processing speed, with vigilance tasks showing the most consistent and dramatic declines. If employed apnea patients are not only sleeping less but also detaching less effectively from work-related rumination, they may be compounding a subtle but cumulative cognitive burden. That burden would persist even after PAP therapy eliminates the breathing pauses, because the therapy addresses the airway but says nothing about the calendar or the smartphone buzzing with after-hours emails.

Connecting these threads produces a provocative reframing of the residual EDS problem. The MAGNETO study identified residual sleepiness as a cognitive risk phenotype, a subgroup of treated patients whose brains show signs of underperformance despite objectively adequate apnea control. Riese and Koehler suggest that this phenotype may partly reflect occupational sleep restriction rather than inadequately treated apnea. If that hypothesis holds up under prospective testing, it would carry immediate clinical consequences. Before escalating to wake-promoting agents, the stimulant medications sometimes prescribed for persistent sleepiness, clinicians might first take a careful occupational sleep history: how many hours does the patient work, does the job involve shifts or on-call duties, how much weekly rest time remains, and how well does the patient mentally disconnect from work in the evening?

The authors are careful to frame their data as hypothesis-generating rather than definitive. Their cohort was treatment-naïve, meaning the sleepiness measurements were taken before PAP therapy began, and the cross-sectional design cannot prove that employment causes residual sleepiness in treated patients. Employment status also correlates with many other variables, from body weight and comorbidities to socioeconomic factors, that could influence both sleepiness and cognition. What the letter does establish is a plausible, quantifiable, and, importantly, modifiable mechanism that has been almost entirely absent from the research agenda on residual EDS. Sleep debt of more than an hour per week, accumulated silently in the schedules of working patients, is exactly the kind of variable that large observational studies rarely capture.

To close that gap, Riese and Koehler propose a concrete research roadmap. Future prospective studies of residual sleepiness in PAP-adherent patients, they argue, should incorporate validated instruments measuring work hours, shift schedules, cumulative sleep debt, psychological detachment, and prosocial work orientation, the tendency to view one’s job as serving others, which intensifies the difficulty of switching off. Such measurements would allow researchers to disentangle how much of the heterogeneity in sleepiness phenotypes stems from occupational factors and how much from biological or treatment-related causes. They would also point clinicians toward a target that costs nothing to modify: restoring recovery time. For the growing population of treated sleep apnea patients who still struggle to stay awake, the most effective prescription may not come from the pharmacy but from a renegotiated boundary between work and rest.

Subject of Research: Occupational sleep restriction as a contributor to residual excessive daytime sleepiness in PAP-treated obstructive sleep apnea

Article Title: Occupational sleep restriction: a missing piece in residual EDS of PAP-adherent OSA?

Article References: Occupational sleep restriction: a missing piece in residual EDS of PAP-adherent OSA?. (n.d.). https://doi.org/10.1007/s44470-026-00153-0

Image Credits: AI Generated

DOI: 10.1007/s44470-026-00153-0

Keywords: obstructive sleep apnea, excessive daytime sleepiness, PAP therapy, sleep debt, occupational health, psychological detachment, Epworth Sleepiness Scale, cognitive deficits, sleep medicine, work hours, CPAP, sleep restriction