Make Caffeine Work

Four rules get you most of the benefit with little of the cost:

• Consider waiting after waking if early coffee leaves you crashing later; the adenosine and cortisol story is plausible but not a proven universal rule
• Cap it near 400mg if you are a healthy adult - and lower if you are pregnant, caffeine-sensitive, anxious, have certain heart conditions, or your clinician has told you to limit it
• Cut it off by early afternoon - late caffeine quietly steals deep sleep
• Use short breaks or lower-caffeine days if you notice tolerance building, rather than treating a specific reset timeline as guaranteed

Drink some water alongside, too - caffeine is a mild diuretic.