When's the optimal time to get your coffee kick? Sometime between 9:30 and 11:30 in the morning should work well, neuroscience doctoral student Steven Miller explains in a supremely helpful blog post.
Careful timing of when you get your caffeine prevents you from building a tolerance to it, Miller explains, in much the same way using painkillers or antibiotics only when they're needed is important to prevent people from becoming resistant to the effects of these important medicines. Except that with caffeine, you're not trying to change your body's pain/pleasure perception or bacterial load. You're messing with its alertness.
Just as you shouldn't hit up I-just-had-surgery-strength prescription painkillers for a mild headache, Miller suggests avoiding coffee during time periods when the body is naturally more alert. Instead, try a cup as the body is coming off these peaks, which are determined by the body's internal clock. Check out Miller's post for more on the science of how that clock works, the hormone it releases periodically throughout the day, and other optimal coffee-drinking hours.