The effects of caffeine can be felt as soon as 15 minutes after it is consumed. The level of caffeine in your blood peaks about one hour later and stays at this level for several hours for most people. Six hours after caffeine is consumed, half of it is still in your body.

How do you know if caffeine is working?

Caffeine acts as a central nervous system stimulant. When it reaches your brain, the most noticeable effect is alertness. You'll feel more awake and less tired, so it's a common ingredient in medications to treat or manage drowsiness, headaches, and migraines.

Does coffee give you a kick?

It is just a temporary effect of your brain's receptors. Macrobiotic nutritionist and health practitioner Shilpa Arora says that it does give you an instant kick and is a superfood you must not cut out from your diet. ... Coffee's impact on brain activity has many scholarly studies to its credit.