#Caffeine
Articles tagged #Caffeine on Vitalspell.
Caffeine improves attention by small but real margins, finds largest meta-analysis to date
A meta-analysis of 31 randomised trials and 1,455 participants found that acute caffeine intake produces modest but reliable improvements in both attention accuracy and reaction time. The dose-response curve tells a more nuanced story: more caffeine keeps speeding you up, but accuracy peaks and then declines.
Caffeine within 12 hours of bedtime harms sleep, often without you noticing
A randomized crossover trial in Sleep found that 400 mg of caffeine disrupts sleep when consumed within 12 hours of bedtime, while 100 mg is safe up to four hours before bed. Most participants could not tell when caffeine was harming their sleep.
L-theanine plus caffeine improved attention within two hours, meta-analysis finds
L-theanine combined with caffeine produced small-to-moderate gains in attention switching and digit vigilance within two hours of ingestion, a meta-analysis of 15 RCTs found. The benefits were real but modest, and confidence intervals revealed substantial uncertainty around the effect sizes.