why should i wait with my coffein intake 90 minutes?

Waiting 90–120 minutes after waking may give you a steadier arc of energy through the day and help protect nighttime sleep. 1

• 1. Natural waking process: Caffeine blocks adenosine’s effects, but taking it right after waking may mask sleepiness rather than allow the morning cortisol rise to help clear residual adenosine. Waiting gives that process time to unfold. 2 3
• 2. Afternoon crash: Delaying caffeine may reduce an afternoon energy crash and the urge to take more caffeine later. 4
• 3. Nighttime sleep: Caffeine has a roughly 12-hour quarter-life, so some of its effects can remain many hours later; afternoon caffeine can disrupt sleep quality. Delaying your first dose may help you avoid needing that later dose. 5 6