Taking a 'coffee nap' (consuming coffee immediately before a short nap) allows one to maximize alertness and reduce sleep inertia upon waking.

noli's read

Science supports this mechanism through the combined action of caffeine and adenosine. Adenosine is a molecule that accumulates in the brain during wakefulness and causes drowsiness; napping helps eliminate some of this adenosine, while caffeine takes approximately 20 to 30 minutes to reach the bloodstream to block the remaining receptors. Studies, notably those published in journals such as 'Psychophysiology' (type: randomized controlled trials), confirm that this technique is more effective at reducing sleepiness than napping or coffee alone. The advice is faithful to the research, as it does not suggest replacing sleep, but rather optimizing a short period of rest. There is no major exaggeration here, provided the nap is limited to 20 minutes to avoid entering deep sleep. This is a well-supported strategy for times of low energy in the middle of the day.

the sources

No named source held this one up — that absence is part of the verdict.