Why does caffeine keep you awake?

Answer 1

Medically, caffeine is useful as a cardiac stimulant and also as a mild diuretic (it increases urine production).

Caffeine is an addictive drug. Among its many actions, it operates using the same mechanisms that amphetamines, cocaine, and heroin use to stimulate the brain. On a spectrum, caffeine's effects are more mild than amphetamines, cocaine and heroin, but it is manipulating the same channels, and that is one of the things that gives caffeine its addictive qualities. If you feel like you cannot function without it and must consume it every day, then you are addicted to caffeine.

To a nerve cell, caffeine looks like adenosine (sleep inducing hormone.) Caffeine therefore binds to the adenosine receptor. However, it doesn't slow down the cell's activity like adenosine would. So the cell cannot "see" adenosine anymore because caffeine is taking up all the receptors adenosine binds to. So instead of slowing down because of the adenosine level, the cells speed up. You can see that caffeine also causes the brain's blood vessels to constrict, because it blocks adenosine's ability to open them up. This effect is why some headache medicines like Anacin contain caffeine -- if you have a vascular headache, the caffeine will close down the blood vessels and relieve it.

So now you have increased neuron firing in the brain. The pituitary gland sees all of the activity and thinks some sort of emergency must be occurring, so it releases hormones that tell the adrenal glands to produce adrenaline (epinephrine).

Answer 2

Caffeine doesn't keep me awake it relaxes me and calms me so i can sleep better . MOST PEOPLE caffeine makes them stay awake but i guess I'm different I 'am the same with some medicines they work on me the opposite of everyone else.

Answer 3

Because it stimulates your central nervous system.

Answer 4

sugar? i dunno.