Episode 154 – How Much Does Caffeine Affect Sleep?

Key Topics Covered

women sleeping with coffee in bed.

A large portion of this episode will be based on a review titled “The effect of caffeine on subsequent sleep: A systematic review and meta-analysis”. The reason is that it is the simplest way to cover this topic. We know that caffeine is very individualized, however having these numbers can be helpful to draw on and get averages from.

How Much Does Caffeine Impact Sleep on Average

  • This review featured 24 studies and they found that within those studies, on average caffeine reduced sleep duration by 45 minutes and sleep efficiency by 7%. 
  • Obviously that’s not really helpful information without adding context around how much caffeine was used in each study, the timing of the caffeine and individual variation.
  • Breaking down 24 studies individually would be too much for this podcast, but we will go through a few things that will start to make this more relevant.

Half-Life of Caffeine and Individual Variation

  • Unrelated to that review, the half-life of caffeine is around 5 hours. This means on average it takes around 5 hours to be half out of your system.
  • That is very individualized though, with half-lives ranging from 1.5-9.5 hours.

What Did the Review Find

Black coffee with clock next to it.

  • Returning back to the review and averages, it included interesting information on how far away from going to sleep caffeine would need to be consumed to have minimal impact on sleep.
  • They found that to avoid impact on total sleep time, a coffee containing 107mg of caffeine should not be consumed within 9 hours of going to bed. A serve of pre-workout, which they counted as 217mg of caffeine, should not be consumed within 13 hours of going to bed.
  • That means if you went to bed at 10:30pm you would need to avoid taking pre-workout from 9:30am. Pretty wild statistic.
  • These stats don’t account for stacking caffeine either. For example, if you had a coffee at 7:30am and THEN added the pre-workout at 9:30am, your total amount would now be higher. The higher the dosage, the longer the duration before it will no longer impact sleep.
  • From a positive perspective, this review found that drinks with low caffeine content like tea had minimal/no impact on sleep when consumed in isolation.

How to Interpret This

  • A lot of the studies included did not have people consuming caffeine regularly. On the one hand, this could mean people were more sensitive to it. But I still wouldn’t disregard these numbers completely.
  • These results are simply averages. They could be pretty irrelevant for you.
  • At minimum though, we know that high doses of caffeine late in the day are likely to impact sleep pretty noticeably
  • Sleep is far more important than the small benefit to performance that caffeine can provide, which is important to keep in mind.

Summary

Caffeine definitely does impact sleep quality and quantity. While there is individual variation, it probably impacts people more than what they realize, particularly since many people have it quite consistently throughout the day. It could be worth tapering back if you feel like your sleep could be improved.

Relevant Blogs / Resources

Studies:

Blogs: