I C Dunican et al, 2018. Caffeine use in a Super Rugby game and its relationship to post-game sleep, European Journal of Sports Nutrition, published online

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To examine the relationship between regular game-related caffeine consumption on sleep after an evening Super Rugby game.

Twenty elite rugby union players wore a wrist-activity monitor to measure sleep for three days
before, three days after and on the night of an evening Super Rugby game (19:00–21:00). Players ingested caffeine as they
would normally (i.e. before and sometimes during a game) and saliva samples were collected before (17:00) and after
(21:30) the game for caffeine concentration.

Compared to the nights leading up to the game, on the night of the
game, players went to bed 3 h later (23:08 ± 66 min vs 02:11 ± 114 min; p < .001) and had 1:30 hh:mm less sleep (5:54 ±
2:59 vs 8:02 ± 1:24 hh:mm; p < .05) and four players did not sleep after the game. Post-game caffeine saliva
concentrations were greater than pre-game levels in 17 players (Pre-game 0.40 µg/mL vs Post-game 2.77 µg/mL; p < .001).
The increase in caffeine saliva concentrations was moderately associated with an increase in sleep latency (p < .05), a
decrease in sleep efficiency (p < .05), and a trend for a decrease in sleep duration (p = .06) on game night.

Caffeine consumption before a Super Rugby game markedly increases post-game saliva caffeine levels. This may
contribute to the observed 3.5 h delay in time at sleep onset and the 1.5 h reduction in sleep duration on the night of the
game. This study highlights the need for a strategic approach to the use of caffeine within a Super Rugby team
considering the potential effect on post-game sleep.

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