Episode 119 – Do You Need to Wait 1-2 Hours After Waking Before Consuming Caffeine

Key Topics Covered

clock inside coffee

This is something that has become quite popular on social media recently.

The proposed mechanism has to do with certain hormones (mainly cortisol and adenosine) being low upon waking which would theoretically reduce the effects of caffeine. 

Therefore by timing it 1-2 hours after waking, we may be able to see more of a benefit from the caffeine intake.

Expanding on Mechanisms

ASAP Science – Mechanisms of Caffeine


  • Cortisol levels peak around 45 minutes (or another timeframe, depending on the source) after waking. Then they start to decrease. 
  • Theoretically, adding caffeine while cortisol is already increasing would not further increase it much. 
  • Instead, if you wait until cortisol starts to drop, you can offset that drop and get a further increase instead. 


  • Adenosine is something that makes us feel tired. Caffeine blocks adenosine by attaching itself to adenosine receptors. 
  • When we wake, adenosine levels are low. Typically, they rise throughout the day. 
  • Therefore one of caffeine’s main benefits isn’t really in play when you have it directly after waking.  

Avoiding the Afternoon Crash 

  • If somebody only consumed caffeine once per day, timing it later could help reduce the 2/3pm crash. 

Cortisol Effects

cortisol on brain

  • Usually, we hear about cortisol as the “stress hormone” and “fat-storing” hormone. 
  • That is an oversimplification of what cortisol does in the body as we know it has positive and negative functions.
  • Overall it is usually discussed as being a negative thing. 
  • From a positive perspective, it makes us feel more alert, it increases glucose metabolism and it reduces inflammation.
  • These are the impacts of cortisol that lay the foundation of this proposed mechanism with delayed caffeine intake.

Cortisol and Caffeine Tolerance 

  • This concept of cortisol increasing after waking, and then dropping, seems pretty consistent in the research. 
  • There is also plenty of research showing that caffeine increases cortisol levels.
  • However, one thing that is often not factored in, is that a large percentage of studies done on caffeine are done in people who have not been consuming caffeine for a lead-in period prior to the testing.
  • Therefore, this may not be relevant to habitual caffeine consumers.

Key Study on the Topic

  • One study had 96 participants (equal split of men and women). They got them to consume various dosages of caffeine leading into the experiment, ranging from 0-600mg per day in a double-blind crossover study.  
  • Then they took 250mg caffeine (or placebo) at 9 am, 1 pm and 6 pm.  
  • The key finding was that there was no difference in cortisol response after the 9 am dosage between caffeine and placebo
  • This is the strongest argument against the cortisol component of this discussion. 
  • Some aspects to consider:
    • To the best of our knowledge, this is the only study that has looked at it from this perspective. Therefore it is a bit early to say this with confidence.
    • Other studies have shown a cortisol increase but were done in people who hadn’t consumed caffeine.
    • Cortisol actually did increase in the 1 pm and 6 pm dosages, although the response was blunted vs placebo. 

Adenosine & Afternoon Crash

Afternoon crash at work desk

  • In relation to adenosine, the theory makes a lot of sense.
  • As adenosine rises throughout the day, we can use caffeine to offset feelings of tiredness.
  • This also doesn’t mean having a coffee upon waking is entirely useless. It is still going to have an effect on perceived effort and alertness.
  • Caffeine will still be in your for several hours AND we can also use multiple caffeine dosages across the day.  
  • The afternoon crash is only relevant if you are limiting yourself to 1 caffeine dose a day.
  • A simple solution for that is to have a second dosage. If you are concerned about the total amount, you could just reduce the amount in each dosage. 


  • It is likely not detrimental to consume caffeine directly upon waking if you are a habitual caffeine drinker.   
  • It just might be slightly less effective than if you waited 60-90 minutes for the adenosine aspect.  
  • It still contributes to your overall caffeine intake, which could be a downside in some cases. 
  • Overall, this topic likely does not matter much for people who consume caffeine regularly. There can be some benefits to waiting, although these benefits are likely reduced if you regularly consume caffeine.  

Relevant Links / Resources

Blog Posts

Studies Mentioned