OYAH INGREDIENT LIBRARY

Caffeine

Caffeine can improve alertness and selected attention measures, but response varies with amount, habitual intake, sleep, timing and individual sensitivity.

Evidence reviewUpdated 11 October 2026
CAlertness / stimulant
Evidence signalConsistent acute alertness effect; sleep cost matters
Research focusAttention, vigilance, reaction time and sleep
Key qualifierTotal daily intake and timing

What it is

Caffeine is a stimulant that mainly blocks adenosine receptors. It occurs in coffee and tea and is added to some supplements. The same amount can feel different across people because habitual use, genetics, medicines and sleep affect response.

What human research suggests

Reviews support short-term improvements in vigilance, attention and reaction time. Memory and complex decision-making findings are less consistent. Caffeine can also delay sleep and reduce sleep quality, especially later in the day. Benefits during sleep loss do not replace sleep.

HOW THIS RELATES TO OYAH

Caffeine in an OYAH formula.

The related product page shows the current ingredient list and directions. Compare those details with each paper before deciding how closely the evidence applies. OYAH does not claim that the finished formula was tested in the linked studies.

Cognitive PerformanceView Cognitive Performance
Ingredient studyTests a defined ingredient, preparation and protocol.Finished-product evidenceWould require a clinical trial of the complete formula.Certificate of AnalysisReports the tests shown for a sample or lot; it does not establish benefit.
SAFETY & CONTEXT

What to consider before use.

Possible effects include anxiety, tremor, palpitations, reflux and sleep disruption. Count caffeine from every source. Avoid combining several stimulant products. Pregnancy, heart-rhythm conditions, uncontrolled blood pressure, anxiety disorders and interacting medicines call for clinical guidance.

This guide is educational and is not medical advice. Speak with a qualified healthcare professional about pregnancy, breastfeeding, medical conditions, medicines, surgery or persistent symptoms.

READ THE SOURCES

Follow the evidence.

Each link opens the publication, indexed record or government guidance. Study findings remain limited to the preparation and protocol researchers examined.

  1. Acute caffeine and attention2025 systematic review and meta-analysis · PMID 40335666 ↗
  2. Cognitive, physical and occupational performance2016 evidence review · PMID 27612937 ↗
  3. Caffeine after sleep loss2020 systematic review and meta-analysis · PMID 31837359 ↗
  4. Caffeine with L-theanine2025 systematic review and meta-analysis · PMID 40314930 ↗
Current product directory

Know the product. Read the evidence.

Compare the current OYAH range, then open the product-specific evidence and ingredient guides. Ingredient studies do not establish the benefits of a finished OYAH formula.