This article looks at evening caffeine supplementation and next-day sleepiness
What’s the deal?
Caffeine is commonly used to improve endurance performance, but taking it in the evening may interfere with sleep and recovery. This study investigated how different doses of evening caffeine affect rowing performance, sleep quality, and next-day sleepiness in trained rowers.
What did they do?
Thirteen trained male university rowers completed four evening (7–8 pm) 2,000 m rowing time trials. Before each trial, they consumed either a placebo, or a low, moderate, or high dose of caffeine (3, 6, or 9 mg per kg body mass). Each participant completed all four conditions on separate occasions. Researchers measured rowing performance, heart rate, sleep quality the following morning, and subjective daytime sleepiness.
What happened?
Rowers performed better and produced more power with moderate and high caffeine doses compared to placebo. However, both moderate and high doses significantly worsened sleep quality and increased next-day sleepiness. The high-dose condition also caused more side effects, including headaches, insomnia, and stomach discomfort. The low dose resulted in only small performance improvements, but had little impact on sleep.
What can you tell me about the people?
Rowers were around 22 years old on average and accustomed to high-intensity training.
What else should I know?
Caffeine was given in capsule form. It is worth noting that the high caffeine dose is equivalent to about 7 cups of coffee!
What will I do differently?
In recent years I have finally experimented with caffeine supplementation for running. Fortunately most races are in the morning, so I probably don’t need to worry about my sleep subsequent quality. Plus, with or without caffeine, I’m usually zonked the next day anyway!
Acknowledgements
This research was published in 2025 by I Karakulak and colleagues from Mardin Artuklu University in Mardin, Türkiye .
This article highlights our personal take on their research, but there is so much more information available! Check it out here and see what you think!
Abstract Athlete 