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Caffeine
A stimulant in coffee, tea, cocoa, and energy drinks. Its effect can last 6 hours or more.
Who reacts
Everyone at high doses. Slow caffeine metabolizers react more, and for longer.
Typical onset
0 minutes to 10 hours after you eat it
Linked symptoms
Poor sleepStrong evidence
Anxiety or jittersStrong evidence
Racing or pounding heartModerate evidence
Heartburn or refluxModerate evidence
HeadacheModerate evidence
DiarrheaWeak evidence
Where you find it
High:Coffee · Energy drink
Medium:Black tea · Green tea
Low:Decaf coffee · Kombucha · Dark chocolate / cocoa
Sources
- Drake et al. 2013, J Clin Sleep Med 9(11):1195 — caffeine 0, 3, or 6 hours before bed