The UK’s National Health Service thinks energy levels are at their lowest at about 2:16 pm. The amount of time it takes for coffee to kick in depends on a number of factors–including age, weight, gender, and caffeine tolerance level–but 15 to 30 minutes is a pretty good window. Pro tip: Supercharge your rejuvenation with a caffeine nap. A cup of coffee followed by a 15-minute snoooze. By the time you wake up, the drug should be kicking in.
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