Effects of Napping on Alertness, Cognitive, and Physical Outcomes of Karate Athletes

Abstract

Purpose It has been suggested that napping is the best recovery strategy for athletes. However, researches on the impacts of napping on athletic performances are scarce. The aim of this study was to determine the effects of a 30-min nap after a partial sleep deprivation, or a normal night condition, on alertness, fatigue, and cognitive and physical outcomes. Methods Thirteen national-level male karate athletes were randomized to experience nap and no-nap conditions, after either a reference or a partial sleep deprivation night. The nap lasted 30 min at 1:00 pm. The postnap testing session started at 2:00 pm by quantifying subjective alertness and fatigue. Cognitive and physical performances were respectively measured before and after the karate-specific test (KST) by simple reaction time (SRT) test, lower reaction test (LRT), mental rotation test (MRT), squat jump (SJ), and counter movement jump (CMJ) tests. Results After a reference night, the nap improved alertness and cognitive outcomes (SRT, LRT, and MRT). No effects on subjective fatigue and physical performances were found. After a partial-sleep deprivation, the nap restored subjective alertness and the decrement in performances caused by sleep loss in most of the tests (MRT, LRT, and KST), but no effects were observed in subjective fatigue and CMJ. After the fatigue induced by KST, there was an ergogenic effect of the nap on the physical performances (CMJ and SJ), and a partial psychogenic effect on the cognitive performances (LRT). Conclusions A 30-min nap enhances cognitive outcomes. It is also an effective strategy to overcome the cognitive and physical deteriorations in performances caused either by sleep loss or by fatigue induced by exhaustive trainings in the afternoon.

A 90 min Daytime Nap Opportunity Is Better Than 40 min for Cognitive and Physical Performance

“…Our results were consistent with those reported by other studies confirming the beneficial effect of napping on cognitive [ 11 , 14 , 16 ] and physical performance [ 11 , 12 , 13 , 15 , 16 , 17 , 28 , 29 , 31 , 32 ], independent of the previous night’s sleep. For example, following a normal night sleep, it has been shown that (i) a 25-min nap opportunity enhanced performance during the 5mSRT [ 12 ], (ii) a 25-min, 35-min and 45-min nap opportunity increased physical performance during the 5mSRT [ 13 ], (iii) a 35-min and 45-min nap opportunity enhanced 5 jump performance [ 11 ], and (iv) a 45-min [ 11 ] and 90-min [ 10 ] nap improved attention estimated by the digit cancelation test (DCT).…”

“…Previous studies are limited by the lack of an objective measurement of the previous night’s sleep [ 11 , 12 , 13 , 15 , 16 , 17 , 28 ], which may confound their results. In this study, we confirmed total time sleep before each condition via the use of actigraphy, similar to previous work [ 14 , 29 , 30 ].…”

“…For example, following a normal night sleep, it has been shown that (i) a 25-min nap opportunity enhanced performance during the 5mSRT [12], (ii) a 25-min, 35-min and 45-min nap opportunity increased physical performance during the 5mSRT [13], (iii) a 35-min and 45-min nap opportunity enhanced 5 jump performance [11], and (iv) a 45-min [11] and 90-min [10] nap improved attention estimated by the digit cancelation test (DCT). After partial sleep deprivation, 30-min of napping improved sprint performance and alertness [14,16], and 20-min and 90-min of napping enhanced repeated sprint performance [15,17].…”

“…Napping is a recovery period defined as a propensity to sleep in response to the post lunch dip process, which was associated with reductions in core temperature and vigilance and an increase in the tendency to sleep [6]. More importantly, sleepiness [7,8], mood states [9], psychomotor [10], cognitive [7,9,11], and physical performances [11][12][13][14][15][16] have been positively associated with napping. Following a normal night sleep, it has been shown that (i) a 25-min nap opportunity enhanced performance during the 5-m shuttle run test (5mSRT) [12], (ii) a 25-min, 35-min and 45-min nap opportunity decreased subjective fatigue, sleep, and stress [11] and increased physical performance during the 5mSRT [13], (iii) a 35-min and 45-min nap opportunity enhanced 5 jump performance [11], and (iv) a 45-min [11] and 90-min [10] nap opportunity improved attention estimated by the digit cancelation test (DCT).…”

A Thirty-Five-Minute Nap Improves Performance and Attention in the 5-m Shuttle Run Test during and outside Ramadan Observance

“…To the best of the authors’ knowledge, this is the first study investigating the effect of a nap opportunity during Ramadan observance on physical and cognitive performance. Although positive effects have been observed on physical performance (i.e., increase of TD and BD after N35 in the all experimental sessions) and cognitive performance (i.e., improvement of attention after N35 at DR and AR), previous studies show that napping might improve physical [ 24 , 25 , 26 , 27 , 28 , 41 ] and cognitive [ 28 , 41 ] performance. The non significant effect of the nap opportunity on some parameters may be related to duration.…”