In this Journal Club we’re taking a TLDR approach to examining a new study that looked at the impact of caffeine on your sleep.
The study we’ll be looking at was titled:
Gardiner, C. L., et al. (2024). “Dose and timing effects of caffeine on subsequent sleep: A randomised clinical crossover trial.” Sleep.
Here is the primary takeaway:
400mg of caffeine (equivalent to around one Tall Starbucks coffee), consumed 12 hours before bed time may still negatively impact your sleep.
Yes, you read that right, 12 hours before bedtime, still impacting your quality of sleep.
To be honest, this result surprised me. My understanding for years has been if you stop drinking caffeine six hours before bed time you should be good, 12 hours came as a shock.
As you can imagine, if you consume that same Tall Starbucks coffee at eight or four hours before bed time, the impacts on your sleep are even worse.
*As a side note, you can read more about caffeine in our Caffeine For Cycling Guide 2.0 **
If you’re serious about scaling back your caffeinated drink intake in order to improve your sleep, it seems that limiting your intake to around 100mg, four or more hours before bed time might be ideal.
You can get an idea of how caffeine timing impacts your sleep by checking out four experimental conditions evaluated in the study:
- 100mg of caffeine consumed four hours before bedtime
- 400mg of caffeine consumed four hours before bedtime.
- 400mg of caffeine consumed eight hours before bedtime.
- 400mg of caffeine consumed 12 hours before bedtime.
The primary lesson from this study is simple. If you’re drinking caffeine in any significant amount in the twelve hours or so before bed, it’s worth experimenting with reducing your caffeine intake if you’re serious about improving your sleep.