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

Nonlinear analysis of EEG during NREM sleep reveals changes in functional connectivity due to natural aging

The spatial organization of nonlinear interactions between different brain regions during the first NREM sleep stage is investigated. This is achieved via consideration of four bipolar electrode derivations, Fp1F3, Fp2F4, O1P3, O2P4, which are used to compare anterior and posterior interhemispheric interactions and left and right intrahemispheric interactions. Nonlinear interdependence is detected via application of a previously written algorithm, along with appropriately generated surrogate data sets. It is now well understood that the output of neural systems does not scale linearly with inputs received and thus the study of nonlinear interactions in EEG is crucial. This approach also offers significant advantages over standard linear techniques, in that the strength, direction and topography of the interdependencies can all be calculated and considered. Previous research has linked delta activity during the first NREM sleep stage to performance on frontally-activating tasks during wake. In the current paper, it is demonstrated that nonlinear mechanisms are the driving force behind this delta activity. Furthermore, evidence is presented to suggest that the ageing brain calls upon the right parietal region to assist the pre-frontal cortex. This is highlighted by statistically significant differences in the rates of communication between the left pre-frontal cortex and the right parietal region when comparing younger subjects (< 23 years) with older subjects (> 60 years). This assistance has been observed in brain imaging studies of sleep deprived young adults, suggesting that similar mechanisms may play a role in the event of healthy aging. Additionally, the contribution to the delta rhythm via nonlinear mechanisms is observed to be greater in older subjects

Beginning teachers' conceptual understandings of effective history teaching: examining the change from 'subject knowers' to 'subject teachers'

This article reports the investigation of change in preservice teachers' conceptions of effective history teaching across a secondary History methods course in a postgraduate diploma of education program. Using concept mapping to plot shifts in their expressed reflections, data were obtained that indicate personal constructs of effective history teaching based around participants' map structures, curriculum understandings, knowledge of subject matter, knowledge of learners, knowledge of pedagogies, and pedagogical content knowledge. The purpose of this article is twofold: to present the findings of research exploring the growth in conceptual understandings of early career history teachers promoted through the use of; and to discuss the participants' response to tangible opportunities to reflect on their own conceptual understandings of history teaching