Sleep restriction and serving accuracy in performance tennis players, and effects of caffeine

Athletes often lose sleep on the night before a competition. Whilst it is unlikely that sleep loss will impair sports mostly relying on strength and endurance, little is known about potential effects on sports involving psychomotor performance requiring high level cognitive skills necessitating judgement and accuracy, as in tennis, and where caffeine is ‘permitted’’. Two studies were undertaken on the effects of 5h sleep (33%) restriction versus normal sleep, on an objective measure of serving accuracy in semi-professional tennis players. Testing (14:00h-16:00h) for both studies comprised 40 serves into a (1.8m x 1.1m) ‘service box’ diagonally, over the net. Study 2 was identical to that of Study 1, except that there was an extra sleep restriction condition. All conditions involved a sugar free drink given 30 min before testing, but with the drink for one sleep restriction containing 80mg caffeine (double blind). Study 1 comprised 16 men and women, in a within Ss counterbalanced design (normal versus sleep restriction). Study 2 involved 12 different men and women undergoing three conditions in a latin square design. Conditions were as for Study 1, with a replicated sleep restriction. All conditions incorporated a sugar-free drink given 30 min before testing, with one restriction including 80mg caffeine (double blind). Both studies showed significant impairments to serving accuracy following sleep restriction, particularly with women. At this dose, caffeine had no beneficial effect. These results reflect laboratory based, non-sports related findings pointing to detrimental effects of sleep loss on executive function.