It contains a very popular stimulant called caffeine. This article explains when the best time to drink coffee is to maximize its benefits and minimize its side effects. Cortisol and coffee Many people enjoy a cup — or three — of coffee upon rising or shortly thereafter. Cortisol is a hormone that can enhance alertness and focus. It also regulates your metabolism, immune system response, and blood pressure 1. The hormone follows a rhythm specific to your sleep-wake cycle, with high levels that peak 30—45 minutes after rising and slowly decline throughout the rest of the day 2.