ABSTRACT
The aim of this study was to examine the effects of partial sleep deprivation (PSD) and time of day on swimming performance, physiological and psychological variables. Eight swimmers (5 males, 3 females) aged 19–28 years were tested on 4 consecutive days, morning (06:30 h) and evening (17:30 h), under conditions of normal sleep and PSD (2.5 h a night). Measurements included grip and back strength, lung function (VC and FEV1), resting heart rate and mood states. Swimming performances over 4 trials at 50 m and 1 trial at 400 m were also measured.
No effects of PSD were noted on grip (dominant hand), back strength, heart rate, lung function, or swim times. Grip, back strength, heart rate and oral temperature values were higher in the evening than in the morning, values increasing by 4.1%, 7.9%, 5.5% and 1.3%, respectively. A similar trend was noted in swim performance; mean 50 m and 400 m times decreased by 1.9% and 3.6% respectively from morning to evening.
Sleep loss affected mood states, with significant increases in depression, tension, confusion, fatigue and anger and decreases in vigour (P < 0.001). Results support the brain restitution theory of sleep and indicate that the diurnal variation in swimming performance is greater than any due to partial sleep loss.
