Does a short bout of exercise after waking help you think more clearly?
A short bout of exercise after waking may support your thinking over the longer term by improving sleep quality, but a direct, measurable effect immediately afterwards has not yet been demonstrated. If you want to do something for your morning focus, caffeine is, for now, the better-supported option.
Morning exercise may support your thinking ability, but through an indirect route. Moderate exercise appears to promote deep sleep, and deep sleep is linked to better working memory and sharper focus. Dream sleep, in turn, is linked to more flexible switching between ideas. This is a theoretical picture, though, not a direct measurement of someone completing a thinking test ten minutes after a morning workout.
When it comes to the first hours of the day: your thinking is not necessarily at its best in the morning. Reaction time and accuracy are, on average, higher in the evening. The measured differences between morning and evening range from 9 to 34% for reaction time and from 7.8 to well over 40% for attention, depending on the task and the study. Some studies find no difference at all. The pattern is therefore strongly dependent on the task and the findings are contradictory.
Whether you eat breakfast before your morning exercise or not makes no measurable difference to your thinking ability afterwards. This conclusion comes from five small studies involving 70 participants in total, so it should be treated with caution.
Caffeine of around 300 mg taken early in the morning improved word recall by roughly 9.5% compared with no caffeine, in a small study with 14 men. It had no effect on other measures of thinking, such as attention and alertness. A specialist pre-sleep supplement containing sleep-promoting ingredients had no measurable effect whatsoever on thinking the following morning.
This answer draws on five studies: one is a theoretical overview (not a direct measurement of exercise shortly after waking), one focuses on time of day, one looks at the effect of eating breakfast before morning exercise (five small studies, 70 participants in total), and two examine caffeine or supplements. The researchers behind the breakfast overview rated the quality of the evidence as moderate; the remaining studies are small (14 to 17 participants). The evidence for a direct cognitive benefit of a short bout of exercise right after waking is therefore thin and has not been measured directly.