Sleep Extension before Sleep Loss: Effects on Performance and Neuromuscular Function.

Purpose: To investigate the effects of 6 nights of sleep extension on motor performance and associated neuromuscular function before and after one night of total sleep deprivation (TSD). Methods: Twelve healthy men participated in two experimental conditions (randomized cross-over design): extended sleep (EXT, 9.8 +/- 0.1 h time in bed) and habitual sleep (HAB, 8.2 +/- 0.1 h time in bed). In each condition, subjects performed 6 nights of either EXT or HAB at-home followed by an assessment of motor performance and neuromuscular function at baseline (D0) and after one night of TSD, i.e. 34-37 h of continuous wakefulness (D1). Maximal voluntary contractions with superimposed femoral nerve electrical and transcranial magnetic stimulations and stimulations on relaxed muscles were investigated before and after submaximal isometric knee extensor exercises performed until task failure. Results: Time to exhaustion was longer in EXT compared to HAB (+3.9 +/- 7.7% and +8.1 +/- 12.3% at D0 and D1, respectively). Performance at D1 decreased from D0 similarly between conditions (-7.2 +/- 5.6% and -3.7 +/- 7.3% in HAB and EXT, respectively). At D1, the rating of perceived exertion during exercise was lower in EXT compared to HAB (-7.2 +/- 7.5%) with no difference at D0. No difference was observed in voluntary activation between the two conditions. Conclusions: Six nights of sleep extension improved sustained contraction time to exhaustion and this result cannot be explained by smaller reductions in voluntary activation, measured by both nerve and transcranial magnetic stimulation. The beneficial effect on motor performance in the extended sleep condition was likely due to reduced ratings of perceived exertion after TSD. (C) 2016 American College of Sports Medicine

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