Why caffeine may not have the effect you expect

And what other options may help instead

Have you ever wondered why, after several cups of coffee, you still do not feel fully awake? Or why you can drink a lot of black tea and still find yourself yawning? There are several possible explanations for why caffeine may not seem to work for you. Some are genetic, while others are learned. There are also plenty of things you can try if you want another way to get an energy boost in the morning or after lunch.

Interested? Take a look at this gallery to find out why caffeine may not be doing the job for you, and what you can do about it.