Other Effects of Caffeine
Caffeine has a mild stimulating effect so will make a person less drowsy and therefore delay sleep. But some people sleep well after evening coffee, others do not.
Excessive caffeine consumption, in the small percentage of the population who are sensitive to the stimulant effects of caffeine, may result in feelings of restlessness, nervousness and insomnia – however this is not the case for the general population.
A minority of people – especially those who consume a high level of caffeine – may get mild symptoms such as headache or feelings of drowsiness if they suddenly abstain from drinking caffeine-containing beverages. A gradual reduction over 2-3 days does not result in these symptoms.
Research published in 2000 (1) reported that those people who reduced their intake gradually reported minimal, if any, caffeine withdrawal symptoms.
Caffeine is a mild diuretic, and although it may slightly increase frequency of urination it does not increase the volume of urine excreted. It is true to say that single doses of caffeine (at least 250-300mg) have a diuretic effect, but doses at the levels commonly consumed in coffee have little or no effect. Indeed regular caffeine consumers become used to the effect, reducing any action even more.
Unlike drugs of dependence, caffeine does not appear to activate dopamine release in a specific area of the brain associated with addiction. To enjoy a cup of coffee on a regular basis may be a habit, but habit and addiction are very different and should not be confused.
Indeed the World Health Organisation (2) has said that: `there is no evidence whatsoever that caffeine use has even remotely comparable physical and social consequences which are associated with serious drugs of abuse.’
1. Dews.P., et al, Journal of Clinical Pharmacology, 39, 2000
2. The ICD-10 classification of mental and behavioral disorders. World Health Organisation, Geneva 1994