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Caffeine

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Highlights

Dont drink caffeine past lunch time

  • Don't drink caffeine after 2-3pm due to it's Half life.

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. - meta-analysis - PubMed

  • Half life: 4-6 hours.
  • Max Limit: 400 milligrams a day. (According to FDA and Andrew-Huberman's: article)
  • Don't drink caffeine for at least 90 minutes after waking up to allow Adenosine to clear out further.

References

Caffeine primarily works by blocking adenosine receptors.

Adenosine is responsible for making your body sleepy.

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The relationship of Caffeine to Adenosine blocking is logarithmic

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Source nih.gov

First 100mg of caffeine is where most of blocking happens, and start to plato after.

Example adenosine block with 2 cups of coffee

From Example Adenosine Block per Day
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To illustrate how 2 cups will have much different effect on adenosine blocking throughout the day than 1 cup let's plot caffeine level in body versus ballpark adenosine blocking correlated with levels of caffeine in body.

Setup

  • On the left vertical axis of the graph we will have caffeine level in body. (in pencil).
  • On the right vertical axis of the graph we will have receptor occupancy percentage. (in blue).
  • Horizontal axis will be time in hours.

Adenosine Receptor blocking (occupancy) in relationship to caffeine is taken from this study.

Example #1 Outlier metabolism (caffeine half life 2 hours)

This will be an outlier in metabolism having half life of 2-hours.

  • In this example 1st cup of coffee will be taken at 0 hour mark.
  • 2nd cup of coffee will be taken at 8 hours mark.

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Shows that there is quite a difference in receptor occupancy (graphed in blue with 2 cups than what it would have been with 1 cup)

Example #2 in range of median half life metabolism of caffeine (caffeine half life 4hours)

In this example we still take first cup at 0 mark and 2nd cup at 8 hour mark. But half life is at 4 hours.

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Looking at daily area under the curve of adenosine blocking 1 cup does look similar to 2 cups. However, if we were to extend the graph we end up seeing that with 2 cups in this hypothetical example we are blocking Adenosine during our sleep, starting our sleep with about 30% adenosine receptor blockade.

Relationships

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  1. Example Adenosine Block per Day
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