It inhibits the release of excitatory neurotransmitters like dopamine, acetylcholine or noradrenalin. (Wikipedia: Adenosine)
Regulates sleep/wake cycle.
And caffeine?
Caffeine is an adenosine antagonist.
It binds to the same receptors as adenosine would, but does not activate them.
Source: The Oatmeal
What that means
Caffeine does not make you more awake
But suppresses the feeling of tiredness
(In your brain, but also in your muscles.)
... while adenosine levels keep increasing
The consequences
Caffeine has a half-life of ~4-8h
(less in smokers; more during menstruation; ...)
Adenosine keeps accumulating
Sooner or later, you will crash
Tiredness is only suppressed
And then masked with even more caffeine
The body reacts
More receptors for adenosine
building a tolerance → need to increase dosage
tolerance within one week
... almost independent of dosage
Consequently
When regular caffeine users were given caffeine this simply returned them to their baseline, and did not enhance their alertness. Non caffeine users saw no benefit from taking caffeine. http://theness.com/neurologicablog/?p=2023
Consequently (…)
The take home is that regular use of caffeine produces no benefit to alertness, energy, or function. Regular caffeine users are simply staving off caffeine withdrawal with every dose – using caffeine just to return them to their baseline. http://theness.com/neurologicablog/?p=2023
Detox
Detoxification takes 2–6 days
Withdrawal symptoms are stronger the higher your usual dose is
Headache, irritability, insomnia
Then, re-normalize your circadian rhythm
(up to four weeks)
Light and shadow
We keep staring at bright screens
We are surrounded by bright LEDs
(many of them blue or white)
Source: The Oatmeal
