The Properties of Coffee That Keep You Awake
Posted on 04. Oct, 2009 by Russell Jackson in Healthy Food
It’s a well-known fact that coffee keeps you awake. It’s similarly well-known that this is down to the fact that coffee contains caffeine. But do you know why it is that caffeine has this effect? Is it the caffeine itself? Or is something else going on in your body to stop you feeling drowsy?
Actually what caffeine does is to suppress the chemical in the brain that helps us to sleep. Scary as it sounds, caffeine serves to temporarily alter the chemical makeup of the brain, and leads to a naturally-occurring chemical, adenosine, not being able to do its job properly.
Adenosine is produced naturally in the body as a result of our daily routine. Our brains feature adenosine receptors, that this chemical binds itself to, which helps to slow down our brain’s nerve cell activity, leading us to get drowsy and fall asleep.
As a by-product of this binding, blood vessels within the brain are dilated, which serves to let more oxygen to the brain whilst you are asleep. It seems funny that one of the chemicals that is produced by exercise – adenosine – has the counter-intuitive effect of causing you to fall asleep, but natural that it would allow more oxygen in.
Nerve cells perceive caffeine as being similar in makeup to adenosine, so they allow it to bind to the adenosine receptors in the same manner. The effect is the opposite to what they expect, however, with caffeine serving to block the adenosine and thus increase nerve cell activity, rather than slow it down.
Caffeine also has the opposite effect from dilating the blood vessels, leading to them constricting. If you have particular types of headache, this is the reason some cures include caffeine, to restrict the flow of pain-causing blood cells getting to the brain.
As the caffeine is blocking the adenosine from slowing down nerve cell activity, there is increased activity within the brain. Our bodies then react by assuming we’re in some kind of threatening situation, so hormones are generated which trigger the release of adrenalin – the well-known ” fight or flight” chemical.
Obviously, we know that a shot of adrenaline is not going to help you sleep, as it causes your muscles to tense up and your heart to beat faster. Which is why coffee can keep you awake; and why sometimes after you have a cup of coffee, you can feel your heartbeat increasing, and may even experience some form of “high”.
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