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Original Research

Influence of Night Soccer Matches on Sleep in Elite Players

Nédélec, Mathieu1; Dawson, Brian2; Dupont, Grégory1

Author Information
Journal of Strength and Conditioning Research: January 2019 - Volume 33 - Issue 1 - p 174-179
doi: 10.1519/JSC.0000000000002906
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Abstract

Introduction

In elite soccer, press demands from media require soccer players to perform several night-time matches under floodlights (e.g., 20:45 for UEFA Champions League; 22:00 for Spanish Liga de Fútbol Profesional) throughout a season, which may have consequences for both sleep and recovery. During and after night matches, players are frequently exposed to various situations and conditions that can interfere with sleep, potentially leading to sleep restriction. Players are required to perform at their peak at times when psychomotor vigilance and subjective alertness tend to decrease as part of a healthy transition from wake to sleep (10,27). Caffeine is a popular psychoactive substance used by players to enhance endurance performance and mental alertness (11); sleep disturbance may occur when caffeine (∼400 mg) is taken up to 6 hours before bedtime, with ∼1-hour objective total sleep time (TST) reduction observed relative to placebo (5). Players are exposed to bright light in the stadium and also after the match, which may have a detrimental impact on subsequent sleep (3). Finally, postmatch routines (i.e., medical care, cold bath, and meal), press requirements (interviews), and travel may potentially lead to a delayed (and very late) bedtime. When playing 2 evening matches per week, a very late bedtime and early wake-up time can lead to repetitive sleep curtailment, which may finally lead to chronic sleep debt.

After an evening match (kick off after 18:00 hours), players fall asleep later, time in bed (TIB) is significantly shorter, and the resulting amount of sleep is significantly less than after day matches and training days among Australian football, rugby union, and amateur soccer players (21,24). To our knowledge, only Fullagar et al. (7) have found a significant reduction in sleep duration and later bedtime after night matches among elite soccer players. However, a subjective measure of sleep (online survey) was used rather than objective measurements. It is currently not known to what extent players' sleep quantity and quality objectively differ after night matches and training days. The lack of data surrounding sleep after soccer match play is concerning, since these periods of sleep loss could potentially compromise muscle glycogen resynthesis and sprint performance (25). Descriptions of the quantity and quality of sleep, especially after elite night matches, are consequently important to make available to coaches and sports science personnel. According to Bishop (2), key gaps in the evidence informing sports practice will only be recognized when the sport-science community frequently consults the evidence base for answers. In respect to sleep after night matches, consulting the evidence base is warranted to obtain qualitative measures of the psycho-socio-physiological acute and chronic stressors experienced and their potential impact on sleep quality and quantity (17).

The purpose of this study was to monitor the sleeping patterns of elite soccer players and to assess whether differences in sleep quantity and quality occurred after night matches in comparison with training days.

Methods

Experimental Approach to the Problem

This study was an observational design. A typical in-season week is outlined in Table 1. The team participated in the Union of European Football Associations (UEFA) Champions League and French Ligue 1. Matches were scheduled by the respective external organizations. Night soccer matches were played at a kick-off time between 18:00 and 20:30 hours, with exposure to 250 floodlights and 2000-lux bright light during home matches (Stade Pierre Mauroy, Lille Metropole, France). When playing 2 matches per week, players were advised to immerse themselves after the match in a cold bath at 10° C for 10 minutes. Players ate their prematch meal 3 hours before the match, which comprised low-glycemic-index carbohydrate foods. Caffeine intake before and/or during the match was recorded as well as hypnotic compound intake (i.e., short half-life nonbenzodiazepine medications) before the night. At the end of the match, players consumed high-glycemic-index carbohydrate foods and proteins (sport drinks, milkshakes, yogurt, soup, and sandwiches). The players were advised to sleep for at least 10 hours per night throughout the training week, based on a study by Mah et al. (16) who showed that obtaining as much nocturnal sleep as possible (with a minimum goal of 10 hours in bed each night) contributes to improved athletic performance, reaction time, daytime sleepiness, and mood.

T1
Table 1.:
A typical in-season week.*

A mixed-method approach was used, combining objective sleep assessment with a survey, to ascertain both sleep quantity/quality and the sleep observations of players after night matches. Nocturnal sleep data were collected after training days for 12 players (73 nights; 6.1 ± 3.2 nights per player). Throughout a 3-week period, 5 night competitive matches (home: 2; away: 3) were played at different kick-off times: 2 matches at 20:30 hours (8 individual recordings); one match at 19:00 hours (4); 2 matches at 18:00 hours (3), resulting in a total of 15 individual night recordings. The 7 players involved in night matches (playing time: 76 ± 29 minutes) had their sleep assessed after night matches and training days. They slept in their usual environment at home after night matches.

Subjects

Twenty elite soccer players (mean ± SD: age, 26.0 ± 4.6 years; range: 19.0–35.0 years) participated in this study. Baseline anthropometric characteristics were height, 179.8 ± 6.6 m; mass, 77.5 ± 9.1 kg; and body fat, 9.6 ± 1.6% (Dual-energy X-ray absorptiometry; Hologic Discovery A, Waltham, WA, USA). Players were informed about the purpose of the study, and the main investigator answered any questions. All players provided written informed consent. Players did not outline any medically diagnosed sleeping disorder. The Ethical Committee (Lille, France) approved the research project before data collection (CCTIRS #10544), and the study followed the recommendations of the Helsinki Declaration.

Procedures

In field-based studies that involve data collection over consecutive nights, activity monitors are typically preferred over polysomnography—the gold standard for monitoring sleep—because they are wearable, noninvasive, and operate remotely without an attendant technician. In this study, player sleep behavior was monitored using self-report sleep diaries and a wrist activity monitor (Actisleep; The ActiGraph, Pensacola, FL, USA), which is worn like a wristwatch on the nondominant wrist during each sleep period and continuously records body movements. The data are sampled from the accelerometer at a frequency of 30 Hz; the device records 60-second epochs and stores 1800 data items per minute. The recorded data were processed automatically with Actilife5 software (Version 5.5.5; The ActiGraph, Pensacola, FL, USA), which indicated whether the participant was awake or asleep for each recorded 60-second epoch. Essentially, all time was scored as awake unless (a): the sleep diary indicated that the participant was lying down attempting to sleep, and (b) the activity counts from the monitor were sufficiently low to indicate that the participant was immobile (20). The actigraphy method has been shown to be reliable; in addition, epoch-for-epoch comparisons between actigraphy and polysomnography show good agreement (81–90%) (1,23). A medium sleep-wake threshold (>= 50 activity counts is scored as wake) was applied to the data set. Sleep variables were measured as follows: TIB, defined as between lights off (bedtime) and sleep end; sleep onset latency (SOL), defined as time between lights off and sleep onset; TST, defined as time spent asleep, as determined from sleep start to sleep end, minus any wake time; and sleep efficiency (SE), defined as TST divided by TIB (expressed as a percentage). Each morning, players rated their overall perceived sleep quality using a visual 10-point analog scale, where 1 = “excellent” and 10 = “very poor.”

Survey techniques are particularly useful in the examination of the “why” questions at the heart of this research. Within the introduction of the survey, the authors explained the purpose of the investigation and how the results might be used. The issue of confidentiality was of critical concern; players were given assurances that any negative impact from the research would not affect their career progression. A literature search using PubMed was performed to establish a complete list of the psycho-socio-physiological acute and chronic stressors that may impact on sleep (18). Players then answered 16 questions on the sleep issues they usually experience after night matches (start times ranging from 18:00 to 20:45 hours) and strategies they used to get better sleep on the night of evening matches. The survey was completed in a relaxed and comfortable atmosphere for the player and took approximately 10 minutes.

Statistical Analyses

Simple descriptive statistics are reported as mean values ± standard deviations (SDs). The normality distribution of the data was checked with the Shapiro-Wilk test. Differences between sleep recordings after night matches and training days were tested for significance using the Student's paired t-test when parametric methods were used, or the Wilcoxon test when nonparametric methods were used. Comparisons between nights after training days and night matches were assessed through the difference in change scores. Effect size (ES) data were calculated to determine the magnitude of the change score and were analyzed using the following criteria: ≥ 0 to ≤0.2 = trivial; 0.21 to ≤0.6 = small; 0.61 to ≤1.2 = moderate; 1.21 to ≤2 = large; 2.1 to ≤4 = very large; and > 4 = nearly perfect (12). Confidence intervals (CIs 90%) were used to specify estimation of changes. Statistical significance was set at p ≤ 0.05.

Results

Sleep

Sleep variables for the 12 players assessed after training days (73 nights) were as follows: bedtime: 00:19 ± 00:59 hours; awakening time: 08:19 ± 00:40 hours; TIB: 08:00 ± 00:52 hours; SOL: 33 ± 31 minutes; TST: 06:32 ± 01:02 hours; SE: 81.7 ± 10.0%; and subjective sleep quality: 4.0 ± 1.5 arbitrary units.

Changes in players' sleep behavior between training days and night matches are presented in Table 2.

T2
Table 2.:
Sleep variables after training days and night matches (N = 7; mean ± SD).*

Bedtime (02:19 ± 01:16) was significantly later for night matches compared with training days (00:17 ± 00:50; p < 0.001, ES = 1.9, CI 90%: 1.2–2.5), whereas awakening time was not significantly different for night matches (08:46 ± 01:03) compared with training days (08:22 ± 00:39; p ≥ 0.05). Time in bed after a night match was significantly less (−01:39 hours; p < 0.001) than after training days, with a noted large difference (ES = 1.7, CI 90%: 1.0–2.3). Total sleep time after a night match was significantly less (−01:32 hours; p < 0.001) than after training days, with a large difference (ES = 1.4, CI 90%: 0.8–2.0) recorded. Mean and individual data for bedtime and TST, for training days and night matches, are presented in Figures 1 and 2.

F1
Figure 1.:
Mean (white bars) and individual cases (N = 7) of bedtime for training days (TD) and night matches (NM). ***Significant difference between groups (p < 0.001).
F2
Figure 2.:
Mean (white bars) and individual cases (N = 7) of total sleep time for training days (TD) and night matches (NM). ***Significant difference between groups (p < 0.001).

Bedtime (02:50 ± 01:01) was significantly later for away matches compared with home matches (00:56 ± 00:49; p < 0.01, ES = 2.1, CI 90%: 1.0–3.2), whereas awakening time was not significantly different for away matches (09:02 ± 01:04) compared with home matches (08:05 ± 00:49; p ≥ 0.05).

Survey

Eighteen players of 20 (90%) indicated worse sleep in the nights after evening matches than after training days. Players also reported taking a long time to fall asleep after night soccer matches (estimated sleep start: 02:30 ± 01:30 hours). To try to get a better sleep on the night after night matches, players reported using hypnotic compounds (15%; N = 3); myorelaxing medications (15%; N = 3); technology, such as television viewing, computer/laptop, and smart phones (75%; N = 15); read something; and/or applied other relaxation methods (10%; N = 2).

During the afternoon before night matches, 95% (N = 19) of players performed a nap, with an intermediate (30–60 minutes; N = 8) or long (≈90 minutes; N = 11) duration.

Discussion

This study allowed for a comparison in sleep quantity and quality between training days and night matches among elite soccer players participating in the UEFA Champions League and French Ligue 1. Here, TIB and TST were lower after night matches than after training days. During heavy schedules, a very late bedtime and early wake-up time can lead to repetitive sleep curtailment, which may finally lead to chronic sleep debt. In addition to objective sleep assessment, a survey was performed to investigate the sleep issues of players after night matches.

Leeder et al. (13) proposed that as good practice, reference data for “normal” athlete sleep behaviors should be obtained, to allow for comparisons with heavy training and competing (home/away) schedules. The elite (Olympic) athletes investigated in their study normally spent 08:36 ± 00:53 hours in bed and slept 06:55 ± 00:43 hours, with a high interindividual variability in sleep measures. Studies have reported that when sleep is reduced to less than 7 hours, cognitive performance is poorer (for a review, see Ref. 8) and secretion of proinflammatory cytokines is increased (26). Consequently, the elite soccer players presently studied (TST: 06:32 ± 01:02 hours) may not reach the sleep characteristics of a “normal” athlete (13) during training. In addition, SE—a sensitive metric for estimating sleep quality—was 81.7 ± 10.0% during training days, which is similar to the value (80.6 ± 6.4%) reported by Leeder et al. (13). Given that a measure below 85% is considered as indicative of disorder, these results confirm that sleep quality is often lower than expected among elite athletes (10).

As regular starters for their club involved in domestic and UEFA Champions League competitions, the players in this study were frequently exposed to various situations and conditions that can interfere with sleep. Using a subjective measure of sleep, Fullagar et al. (7) found a significant alteration in sleep duration (−181 minutes; p < 0.001, d = 4.31), SOL (+10 minutes; p = 0.03, d = 1.60), and sleep restfulness (p < 0.001, d = 3.56) for night matches—kick off after 18:00 hours—when compared with training days among elite soccer players. To our knowledge, this study is the first to objectively confirm these previous results. Sleep in the night after matches commenced between 18:00 and 20:30 hours was worse (large effects) when compared with training days. A significant reduction in sleep duration (−01:32 hours; p < 0.001, ES = 1.4) was notably observed. After a night match, an elite soccer player may consequently experience insomnia-like symptoms—especially difficulty in initiating sleep—because of hyperarousal with the healthy transition from wake to sleep being substantially inhibited by 2 processes, namely, cognitive arousal and attentional bias (10). In addition to engagement and arousal induced by the match, environmental conditions (e.g., bright light in the stadium) and behaviors before and after an evening soccer match (e.g., napping, caffeine consumption, and alcohol consumption) may potentially explain sleep impairment after matches when compared with training days (17). In this study, mean wake-up time after a night match was 8:46 ± 01:03, due to morning recovery sessions being planned at 10:00 hours (Table 1). A combination of very late bedtime and early wake-up time can lead to repetitive sleep curtailment in players, which may finally lead to chronic sleep debt (22).

The survey responses were used to explain the reasons for difficulty in initiating and/or maintaining sleep in such circumstances. In response to the question about which strategies they used to get a better sleep on the night after evening matches, players revealed that 75% (N = 15) of them use technology (i.e., television viewing, computer/laptop, and smartphones) from ≈30 minutes to several hours before going to sleep, which may have a detrimental impact on sleep (3). These results corroborate previous reports obtained before competition (6) and suggest that athletes may not have appropriate methods for better managing their sleep. Future studies are required to assess the similarities and differences of sleep hygiene strategies (e.g., cognitive behavioral therapies) among elite soccer players who face specific sleep constraints both before and after competition. Individualized sleep interventions that focus on education, awareness, and practical guidance should also be provided to each athlete (24). Players should also receive information on pharmacological treatments. Three of the players (15%) stated that they took sleeping pills, which is higher than the intake of sleep medication use reported in the general population (≈10% (19)). However, not all medications are recommended in sports (14) and the potential detrimental effects of sleeping medications (e.g., hangover effect; altered coordination and reaction time performance) must be recognized (9).

Daytime napping is commonly encouraged as a strategy to extend sleep. The survey responses revealed that 95% (N = 19) of players took a nap before night matches, with an intermediate (30–60 minutes) or long duration (≈90 minutes), which may be associated with deleterious side effects (15). However, future longitudinal studies are required to ascertain the potential benefits of long naps for elite soccer players experiencing regular sleep curtailment because of night matches.

In this study, only 7 players (of 12) were followed after night matches and training days throughout the study period because of tactical reasons. In addition, the number of night(s) monitored after night matches was not consistent across players. As a result, some players contributed more nights to the analyses than others, which is a limitation of this study, especially given the high interindividual variability in sleep measures. This limitation is tempered by the use of elite soccer players in ecologically valid conditions. In addition, the naps taken during the afternoon before night matches and during the day after night matches were not recorded using actigraphy.

Collectively, these data suggest that usual player sleep patterns during training days are disturbed by the specific circumstances of night matches. Sleep curtailment encountered by players after night matches may lead to a cycle of poor sleep, resulting in extended sleep periods (i.e., sleeping late in the morning and long nap) on off days (4) in an attempt to “catch up,” which may then promote more nonrestorative sleep occurring in subsequent nights.

Practical Applications

Time in bed and TST are lower after night matches (kick off after 18:00 hours) than after training days among elite soccer players. Consequently, during heavy schedules, a very late bedtime and early wake-up time can lead to repetitive sleep curtailment, which may finally lead to chronic sleep debt. These considerations should be factored into training schedules. Furthermore, elite soccer players may not necessarily have or use appropriate methods for better managing their sleep after night matches. Education on recommended sleep hygiene practices should be offered.

Acknowledgments

The authors have no conflicts of interest that are directly relevant to the content of this article. No financial support was provided for this study. Results of this study do not constitute endorsement of the product by the authors or the National Strength and Conditioning Association.

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Keywords:

recovery; fatigue; football; stress; survey

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