Why does caffeine make me sleepy?

Coffee is traditionally thought of as a pick-me-up, but many people find that it can actually make them feel tired. Caffeine seems to affect people in different ways, but overall there are 3 main reasons this happens.

1 - It messes with your adrenal glands

Caffeine stimulates the adrenal glands to release adrenalin, the 'flight or fight' hormone that prepares the body to react to a threat. It increases your heart and breathing rates, dilates the pupils and increases blood flow to the muscles. Ideally this adrenalin release happens only very occasionally during times of great physical stress.

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