If you have spent much time in the lifestyle optimisation type of space, you will likely have seen people recommending refraining from caffeine consumption directly after waking.
Recommended timeframes tend to vary anywhere between 30 and 90 minutes.
The logic simply is that if you refrain from caffeine until that time:
- You will get more benefits from that dosage of caffeine.
- You will avoid “wasting” a dosage of caffeine which will have less benefit but still contribute to building a tolerance to caffeine.
This post will explore whether there are actually benefits to this approach, or if it actually does not matter.
Proposed Mechanism
There are two aspects of the proposed mechanism.
The first one is related to cortisol:
- When we wake up, our cortisol levels are naturally increasing.
- These 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 waited until cortisol starts to drop, you can offset that drop and get a further increase instead.
The second one is related to adenosine:
- Caffeine can block adenosine’s functions.
- Adenosine is typically involved in making us feel tired.
- When we wake, our adenosine levels are low and typically rise throughout the day.
- Because of this, if we have caffeine directly after waking, it will not have the benefit of blocking adenosine, since adenosine is so low anyway.
Quick Note on Cortisol
Something that is so interesting about this topic is that it is really the only time I see people in the health and performance space hyping up cortisol as a good thing.
Cortisol has both positive and negative functions. Typically, in the health space, people focus on the negative aspects.
The main positive function of cortisol is that it helps us feel more alert and energised. This is why people hype it up in this context.
I wanted to bring this up because if a key part of the proposed mechanism involves increasing cortisol levels, that seems at odds with what many people would typically aim to avoid—unless they understand the broader context.
Cortisol and Caffeine Tolerance
Much of the research on supports this concept of cortisol levels increasing and then dropping, with caffeine being a tool that can increase cortisol.
One thing worth being aware of though is that often caffeine research is done on participants who have not been consuming caffeine in the leadup to the study though.
A study directly looking at this found that if you habitually consumed caffeine, there was no increase in cortisol levels post consuming 250mg of caffeine at 9am.
That study is actually a bit of a curve ball for this topic. There is not a lot of research looking at things from that angle.
If the impact of caffeine on cortisol is reduced significantly if your tolerance is higher, it largely reduces the impact of this overall mechanism.
It’s worth noting that in that study, cortisol levels did increase when participants consumed caffeine later in the day—morning caffeine simply had no effect.
Practical Summary and Interpretation
This is a short blog post because the answer seems simple.
- It is not detrimental to consume caffeine directly upon waking. It just might be less effective than if you waited 60-90 minutes. It still contributes to your overall caffeine intake, which could be a downside in some cases.
- Since adenosine levels are low directly after waking, the benefit of caffeine-blocking adenosine is irrelevant at that time.
- Cortisol levels increase after waking and seem to peak ~45 minutes later. Theoretically, consuming caffeine after this time can increase these levels further. But if you are a regular consumer of caffeine, this increase in cortisol from caffeine is likely significantly blunted.
Overall, this topic likely does not matter much for people who consume caffeine regularly. There can be benefits to waiting, although these benefits are likely reduced if you regularly consume caffeine.
Meanwhile, if you significantly prefer having caffeine immediately, it’s still fine to do that.
