Caffeine
The world's most widely consumed psychoactive substance. Caffeine blocks adenosine receptors in the brain, preventing the drowsiness signal and increasing alertness, focus, and reaction time. When combined with L-Theanine, it produces one of the most reliable and well-studied nootropic stacks available. Most adults consume 200-400 mg daily through coffee, tea, and other beverages.
Dosage
Standard nootropic dose: 50-200 mg. With L-Theanine: 100 mg caffeine + 200 mg L-Theanine. FDA safe limit: up to 400 mg daily for healthy adults. Avoid after 2pm to protect sleep.
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Half-Life
3-7 hours (average 5 hours, highly variable by individual)
Administration
Oral (coffee, tea, capsules, tablets, powder). Onset: 15-45 minutes. Peak effects: 30-90 minutes.
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Mechanism of Action
Caffeine is a non-selective adenosine receptor antagonist with highest affinity for A1 and A2A subtypes. Adenosine accumulates during wakefulness and promotes sleepiness by binding to A1 receptors (inhibiting adenylyl cyclase and reducing neuronal excitability) and A2A receptors (modulating dopamine D2 receptor signaling in striatum). Caffeine competitively blocks these receptors, preventing the drowsiness signal. This disinhibition indirectly increases dopamine, norepinephrine, and acetylcholine neurotransmission via downstream pathways. Caffeine also inhibits phosphodiesterase (PDE) enzymes—particularly PDE4 in the brain—reducing cAMP degradation. Elevated intracellular cAMP amplifies catecholamine signaling through PKA-mediated phosphorylation of CREB and other transcription factors, enhancing alertness and cognitive performance.
Regulatory Status
GRAS ingredient. Available worldwide without restriction. FDA recognizes up to 400 mg daily as safe for healthy adults.
Risks & Safety
Common
Anxiety, jitteriness, insomnia, increased heart rate, digestive issues, dependency and withdrawal headaches.
Serious
Cardiac arrhythmia at very high doses (>1200 mg). Dangerous at 5-10 g.
Rare
Panic attacks, rhabdomyolysis with extreme doses.
Compare Caffeine With
Research Papers
9Published: January 30, 2015
AI Summary
The present review summarizes the main findings concerning caffeine's mechanisms of action (focusing on adenosine antagonism, intracellular calcium mobilization, and phosphodiesterases inhibition), use, abuse, dependence, intoxication, and lethal effects.
Published: December 10, 2024
AI Summary
A Google Scholar search using the keywords "caffeine" and "exercise" yields over 200,000 results, emphasizing the extensive research on this topic. Does waiting 1.5-2.0 hours after waking to consume caffeine help you avoid the afternoon "crash?" To answer these questions, we performed an evidence-based scientific evaluation of the literat...
Published: October 4, 2001
AI Summary
There is less information about the effects of caffeine on strength; however, recent work suggests no effect on maximal ability, but enhanced endurance or resistance to fatigue. The limited information available suggests that caffeine non-users and users respond similarly and that withdrawal from caffeine may not be important.
Published: April 6, 2018
AI Summary
At the pharmacodynamic level, there are several polymorphisms at the main brain target of caffeine, the adenosine A2A receptor or ADORA2. Genetic studies, including genome-wide association studies, identified several loci critically involved in caffeine consumption and its consequences on sleep, anxiety, and potentially in neurodegenerative and ...
Published: July 12, 2019
AI Summary
In recent years, a number of meta-analyses have demonstrated that caffeine's ergogenic effects on exercise performance are well-established and well-replicated, appearing consistent across a broad range of exercise modalities.
Published: August 29, 2012
AI Summary
In the last period a market of caffeine-containing products, particularly energy drinks and food supplements increased. Results of scientific research are not clear.
Published: July 7, 2024
AI Summary
Caffeine, the main psychoactive component in coffee, has garnered significant attention for its potential impact on the most prevalent mental health conditions like anxiety and depression. However, the relationship between caffeine consumption and the risk of depression is intricate, with some studies suggesting a potential protective effect of ...
Published: October 8, 2020
AI Summary
Our review focuses on the effect of caffeine consumption on several neurological and psychiatric disorders with respect to sex differences to provide a better understanding of caffeine use as a risk or protective factor for those disorders. The findings may help establish new strategies for developing sex-specific caffeine therapies.
Published: December 6, 2018
AI Summary
In this integrative review, we examine evidence illuminating the relationship between caffeine consumption and subsequent quality and quantity of nighttime rest. Secondly, we consider evidence as to whether performance deficits caused by sleep deprivation linked to caffeine can be reversed by caffeine consumption during the subsequent daytime pe...
Frequently Asked Questions
What is Caffeine used for?
The world's most widely consumed psychoactive substance. Caffeine blocks adenosine receptors in the brain, preventing the drowsiness signal and increasing alertness, focus, and reaction time. When combined with L-Theanine, it produces one of the most reliable and well-studied nootropic stacks available. Most adults consume 200-400 mg daily through coffee, tea, and other beverages.
What are the side effects of Caffeine?
Common: Anxiety, jitteriness, insomnia, increased heart rate, digestive issues, dependency and withdrawal headaches. Serious: Cardiac arrhythmia at very high doses (>1200 mg). Dangerous at 5-10 g. Rare: Panic attacks, rhabdomyolysis with extreme doses.
How is Caffeine administered?
Caffeine is administered via oral (coffee, tea, capsules, tablets, powder). onset: 15-45 minutes. peak effects: 30-90 minutes..
What is the half-life of Caffeine?
The half-life of Caffeine is 3-7 hours (average 5 hours, highly variable by individual).
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Bromantane
A unique Russian-developed compound that is both an adaptogen and a mild stimulant — it enhances dopamine synthesis (upregulating tyrosine hydroxylase) rather than releasing or blocking reuptake of existing dopamine. This makes it fundamentally different from traditional stimulants and gives it a smoother, less addictive profile. Used by Russian athletes until WADA banned it.
Forskolin
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Modafinil
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NALT
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Nicotine
Nicotine — independent of tobacco — is one of the most potent cognitive enhancers known. It enhances attention, working memory, reaction time, and fine motor skills within minutes. Research shows it is neuroprotective and may reduce the risk of Parkinson's disease. Available as gum, patches, and lozenges for non-smokers seeking cognitive benefits without any tobacco exposure.