Conclusion: To avoid reductions in total sleep time, coffee (107 mg per 250 mL) should be consumed at least 8.8 h prior to bedtime and a standard serve of pre-workout supplement (217.5 mg) should be consumed at least 13.2 h prior to bedtime. The results of the present study provide evidence-based guidance for the appropriate consumption of caffeine to mitigate the deleterious effects on sleep.
PubMed 36870101 ↗Caffeine
People mainly take Caffeine for energy, focus, anxiety. Based on 761 first-hand reports and 680 meta-analyses & systematic reviews in the medical literature. Ranked #77 of 1,974 overall.
Of reports that state an outcome, 44% are positive.
What Caffeine does, according to users
Of the people who reported each effect, the share who said it got better.
6 more with fewer than 3 reports
What the research says
Systematic reviews and meta-analyses from PubMed, with their published conclusions.
3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.
Conclusion: Hence, caffeine may have utility as an ergogenic aid for endurance running events. More evidence is needed to establish the ergogenic effect of caffeine on endurance running in women or the best dose to maximize the ergogenic benefits of caffeine supplementation.
PubMed 36615805 ↗Conclusion: The authors recommend that individuals avoid frequent energy drink consumption (5-7 energy drinks/week) and avoid co-consumption with alcohol; increased regulatory standards should be placed in the sale of energy drinks, particularly with regard to the pediatric population.
PubMed 33211984 ↗Conclusion: There are several acute treatments for migraine, with varying strength of supporting evidence. Use of triptans, nonsteroidal anti-inflammatory drugs, acetaminophen, dihydroergotamine, calcitonin gene-related peptide antagonists, lasmiditan, and some nonpharmacologic treatments was associated with improved pain and function. The evidence for many other interventions, including opioids, was limited.
PubMed 34128998 ↗Dosage people report
As stated by users — not a recommendation. Follow the label or your doctor.
Reported side effects
How often each side effect came up across all reports.
What users say
Verbatim quotes, shortened only — each links to the original discussion.
“For me (210lbs), 100-150mg. IMO above 200mg js too much.”
“I find caffeine has a pretty negative impact. I cut it off after 9am”
“when I take a strong vasoconstrictor such as coffee, it will eliminate the headache within 30 minutes”
“I am also a stimulant whore (Ephedrine, caffeine, tea; lots of all three)”
“The evidence base seems rival that of L-theanine-caffeine.”
Top discussions (5)
- Three weeks ago I asked why some people still wake up foggy after 8 hours of sleep. I went through 300+ replies. Here’s what kept coming up. ↗
- Creatine supplementation (25 grams or 0.35 g/kg body weight) rapidly reverses cognitive impairment caused by 21 hours of sleep deprivation—boosting brain creatine levels within just 3 hours (new Rhonda Patrick interview) ↗
- I cut out caffeine and my life has 1000% changed for the better ↗
- Have you guys ever tried just taking… nothing? ↗
- Rating every nootropic I've taken ↗
Other options for energy
User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 2, 2026. How we rate