Chronic caffeine exposure can produce a decreased responsiveness to many of caffeine's effects (i.e., tolerance). This has been observed in both nonhumans and humans. Research with nonhumans has clearly demonstrated that chronic caffeine administration can produce partial tolerance to various effects of caffeine and can produce complete tolerance to caffeine's stimulating effect on locomotor activity in rats. A number of studies also suggest that tolerance to caffeine develops in humans: Daily doses of 250 milligrams of caffeine can increase systolic and diastolic blood pressure, however tolerance quickly develops to these effects within four days. The stimulating effects of caffeine on urinary and salivary output also diminish with chronic caffeine exposure. Although tolerance appears to develop to some of the central nervous system effects of caffeine, this aspect of caffeine tolerance has not been well explored. Comparisons of the effects of caffeine between heavy and light caffeine consumers provide indirect evidence that repeated (regular) caffeine use diminishes the sleep-disturbing effects and alters the profile of self-reported mood effects. For example, 300 milligrams of caffeine may produce self-reports of jit-teriness in people who normally abstain from caffeine but not in regular caffeine consumers. High chronic caffeine doses (900 mg per day) can eliminate the self-reported mood effects (tension, anxiety, nervousness and jitteriness) of 300 milligrams of caffeine given twice a day.

Anxiety and Depression 101

Anxiety and Depression 101

Everything you ever wanted to know about. We have been discussing depression and anxiety and how different information that is out on the market only seems to target one particular cure for these two common conditions that seem to walk hand in hand.

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