Caffeine and sleep: A delicate balancing act for athletes

Caffeine is one of the most popular ergogenic aids in the world, but it has the potential to impact sleep quality and recovery time, resulting in lower physical and cognitive function. So how do athletes strike the best balance?

Original study

Caia, J., Halson, S. L., Holmberg, P. M., & Kelly, V. G. (2021). Does Caffeine Consumption Influence Postcompetition Sleep in Professional Rugby League Athletes? A Case Study. International Journal of Sports Physiology and Performance, 17(1), 126-129.

Click here for abstract

Background & Objective

Caffeine is one of the most popular ergogenic aids in the world. Worldwide consumption is crazy, with many everyday people consuming it daily and athletes using it as a stimulant before training and competition (infographic below). Personally, I have seen athletes consume multiple cans of energy drinks each day without any understanding as to how much caffeine they have consumed.

Caffeine consumption can affect numerous sleep indices, such as sleep onset latency and efficiency, rapid eye movement sleep, total sleep time, insomnia, anxiousness, and activity in athletes. As a result, caffeine has the potential to reduce sleep quality and recovery time, resulting in lower physical and cognitive function, especially when caffeine has been consumed in the evening.
The aim of this study was to (1) explore sleep in rugby league athletes before and after an evening match, and (2) investigate the relationship between changes in salivary caffeine concentration and sleep on the night of competition.

What They Did

Fifteen professional rugby league athletes were recruited – all players were regular caffeine consumers prior to taking part in study.

Prior to and during an evening (7:50 pm kick off) rugby league match, players consumed ad libitum (as much or as often or desired) a commercially-available pre-workout supplement, and/or tablets which contained approximately 175mg and 100mg of caffeine per serving respectively.

Saliva samples were collected from the players using a synthetic swab for 45 seconds, one-hour before and 30 minutes after the game, and then frozen ready for later analysis. High-performance liquid chromatography was used to examine saliva samples for caffeine.

Sleep was evaluated on three occasions: the night before the match, the night of the match, and the night following the match using an activity monitor (Actiwatch 2) worn on the players’ wrists, as well as a self-report sleep diary. This allowed both an objective estimation of sleep and also a subjective self-report of player sleep time.

What They Found

One hour prior to competition, the salivary caffeine concentration of players was 2.1 μg/mL. Compared with pre-competition measures, post-competition salivary caffeine concentration was significantly increased (8.1 μg/mL)
Evening competition caused significant adjustments in sleep-wake cycles, as well as shorter sleep duration: on the night of the match, players slept an average 4 hours 27 minutes, which was significantly less than the night before (where it was 210 mins longer) and after (161 mins longer) the match.

Caffeine supplementation prior to and during competition leads to substantial increases in post competition salivary caffeine concentration. Although not significant, there was a trend for caffeine consumption to reduce sleep duration and increase sleep latency. Additionally, in regard to changes in salivary caffeine concentrations and wake time and time in bed, only minor relationships were found.

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Practical Takeaways

• Although a nice study, it is very difficult to control the habitual caffeine consumption of athletes within elite sporting environments. As such, the variance in post-match salivary caffeine concentration may be a consequence of higher basal levels of salivary caffeine, while the lack of standardisation relating to the type, timing, and dosage of supplementation in the current study should also be highlighted.
• As correlations between caffeine consumption and sleep characteristics were all non-significant, the authors rightly highlight that other factors are likely contributing to poor sleep characteristics for players including: exposure to floodlights, post-match alcohol consumption and sleep environments. I would also add from personal experience with rugby players, adrenaline of the match, muscle soreness and mobile phone use in bed are common issues I see in day-to-day practice.
• Practitioners working with athletes who consume caffeine before evening competition should look to provide educational programs to improve sleep hygiene practices. In practice, I have always seen better uptake of education when things are kept simple and easy to understand. Caffeine consumption timelines are a good idea for example.
• Finally, caffeine can be consumed through many forms including fluids (coffee, energy drinks etc), gum, gels and tablets. Working with your athlete to provide them with individualised strategies may result in a lower intake in the evening and support improved sleep characteristics. For example, if a player currently consumes an energy drink with 200mg of caffeine in, but actually feels they only need 100mg, then they would be better to take on a caffeine gum rather than the energy drink. Be careful with the actual caffeine content of coffee pods! They are not all what they say they are!

James Morehen’s Comments

“I liked reading this paper and it reminds me of many conversations that I have had with rugby players regarding caffeine intake. Of course, the focus on match play is to perform, and this results in many players consuming over 300 or 400mg of caffeine pre-match, about 3-6mg/kg body mass, which is aligned to a recent position stand and article below. It is not surprising that they struggle to sleep post-match.

“What do you do then? Do we ask players to not take caffeine so they can sleep better post-match or should we be allowing them to sleep in the following day and catch up on the sleep this way? This is certainly a strategy that is favoured by players; instead of getting them up early on a recovery day and bringing them into the club, allowing them to completely rest at home and lay in for as long as they want to. Hopefully studies in this area are completed soon to answer this research question.”

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