If you reach for a cup of coffee first thing in the morning, then count yourself as one of the millions who use caffeine to kick-start their day. But does it help or hinder you? Caffeine is a powerful stimulant. It speeds up thinking, boosts motivation, and lifts mood, but it does so by temporarily blocking one of the body’s naturally calming brain hormones—adenosine. Within 10 minutes of slurping your early-morning beverage, caffeine is coursing through your blood and sets to work on your brain by blocking adenosine. But the problem is that, at this time, the energizing hormone cortisol is at its peak, while adenosine is at its lowest. A strong coffee or tea on top of all that cortisol doesn’t make you more alert—it simply throws a few matches onto an already raging bonfire, increasing your chances of anxiety and jitteriness. Your espresso is worse than pointless. You’re much better off waiting a few hours until cortisol has waned and adenosine has started to rise, and then you can reap the full benefit of caffeine’s boost.

caffeine fix The best time to reap the energizing rewards of caffeine is in the 2–4 hour window after waking, when cortisol falls away and adenosine starts to rise.