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Drivers experiencing sleepiness are advised to take a break and have a caffeinated drink followed by a short nap (caffeine nap). However, previous research advocating this countermeasure has not considered participants with obstructive sleep apnoea (OSA), the most prevalent sleep disorder. Across three studies the effectiveness of caffeine, nap opportunity and caffeine nap countermeasures on subjective sleepiness (KSS), objective sleepiness (Alpha and Theta activity) and driving performance (standard deviation of lateral position and out-of-lane events) are considered. Twenty-one CPAP treated OSA participants (mean age\u2009=\u200959\u00a0years) engaged with a protocol of six laboratory visits: one after a normal night\u2019s CPAP-treated sleep and five after sleep restriction (4\u00a0h CPAP-treated sleep), driving a monotonous simulated scenario before and after a countermeasure. Results showed that two cans of coffee (255\u00a0mg caffeine) mitigated driver sleepiness more than one can (127.5\u00a0mg) and little benefit to 30\u00a0min compared with 15\u00a0min nap opportunity. An optimised caffeine nap of two coffees followed by a 15\u00a0min nap opportunity provides some temporary benefit, but for OSA drivers a caffeine nap offers little practical improvement compared to two coffees alone. All countermeasures are temporary and cannot replace a good night of sleep before driving.<\/jats:p>","DOI":"10.1038\/s41598-026-42894-1","type":"journal-article","created":{"date-parts":[[2026,3,21]],"date-time":"2026-03-21T08:54:57Z","timestamp":1774083297000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Optimising the caffeine nap for counteracting driver sleepiness in CPAP treated obstructive sleep apnoea patients"],"prefix":"10.1038","volume":"16","author":[{"given":"Ashleigh J.","family":"Filtness","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Karl A.","family":"Miller","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sally","family":"Maynard","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Adam","family":"Asmal","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Thomas","family":"Kerwin","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Andrew","family":"Hall","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anna","family":"Anund","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"297","published-online":{"date-parts":[[2026,3,21]]},"reference":[{"issue":"8","key":"42894_CR1","doi-asserted-by":"publisher","first-page":"687","DOI":"10.1016\/s2213-2600(19)30198-5","volume":"7","author":"Benjafield","year":"2009","unstructured":"Benjafield, et al. 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