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.

However, when we consume excessive amounts of caffeine we promote a sustained adrenalin response, which exhausts the adrenal glands. As a result, these glands are unable to produce even the small amounts of adrenalin required to help us maintain focus and concentration, which in turn creates feelings of physical fatigue and malaise.

2 – It messes with your insulin

A secondary effect of caffeine consumption is that it can dampen the sensitivity of insulin. This hormone is involved in detecting sugar in the bloodstream and ensuring its uptake for energy production. If insulin is not working properly, we have less sugar available for energy and will feel tired.

3 – It messes up your sleep

Finally, caffeine consumption – especially at night – can reduce the amount of slow-wave sleep we get, which we need to be properly rested and rejuvenated. A consistent lack of this deep sleep will definitely contribute to feelings of fatigue.

A combination of some or all of these three physical effects of caffeine on the body can give you a recipe for fatigue.