title_body: How long do the effects of caffeine take to appear?
upvoted_answer: I'm sure there are a lot of studies out there - but ultimately it's personal.  It's like asking, how long after drinking a glass of wine do you start to feel the affects? 
  
  Averages can be arrived at but ultimately everyone is different.
  
  As for me, it may be psychological, but I start to feel the affects seconds after my first sip. (Assuming it's high octane coffee and not the lukewarm water found in some diners.)
  
  I've seen several articles say that coffee takes ten minutes to kick in. Others say 45 minutes.
  
  I don't know how they're measuring things but speaking for myself, and numerous others, the psychological affects kick in much sooner. I don't think coffee would be as popular as it is if it took 10-45 minutes to kick in. 
  
  
    It takes around 45 – 60 minutes for caffeine to kick in after it is consumed.
    https://www.scienceabc.com/humans/how-does-caffeine-work-affect-brain-body-adenosine-receptors.html
    
    see also: https://www.caffeineinformer.com/caffeine-metabolism 
    and: http://www.dailymail.co.uk/health/article-1100767/A-cup-coffee-works-just-10-minutes-drink-greater-impact-men.html
  
  
  The scienceabc.com article continues with:
  
  
    One of the reasons coffee remains so popular is that the effects of caffeine can often be felt for 4-6 hours. 
  
  
  4-6 hours? Ha. Maybe in a controlled environment, where one can measure things to the last drop. In the work environment coffee addicts need to a boost in far less time than that.