Sleep habits and sports performance in athletes: a survey study

GIOVANNI BRUNO1,2, SOFIA DALLA LIBERA1, GIOVANNI MORO1, MICHELE BASILICATA3,4, PATRIZIO BOLLERO4,5, ANTONIO GRACCO1, ALBERTO DE STEFANI1,6

1Department of Neuroscience, School of Dentistry, University of Padua, Italy; 2Department of Industrial Engineering, University of Roma Tor Vergata, Italy; 3UniCamillus-Saint Camillus International University of Health Sciences, Rome, Italy; 4UOSD Special Care Dentistry, Department of Experimental Medicine and Surgery, University of Roma Tor Vergata, Italy; 5Department of System Medicine, University of Rome Tor Vergata, Italy; 6Department of Pharmacological Sciences, University of Padua, Italy.

Summary. Introduction. Sleep has a crucial importance in human life, covering several physiological functions, which are sometimes altered by associated disorders, including Obstructive Sleep Apnea Syndrome (OSAS). In particular, athletes require restorative sleep in order to achieve competitive sport performance. The aim of this study is to establish whether physical activity can play a protective role in OSAS. Athletes’ routines are analyzed, particularly in relation to sleep and oral hygiene, to investigate the prevalence of OSAS and caries, respectively. Materials and methods. A questionnaire was distributed to a mixed population of both athletes and non-athletes. The questionnaire consists of three parts: the first investigates the individual’s level of physical activity; the second part includes a screening for OSAS, based on the Epworth Sleepiness Scale (ESS) and the STOP-BANG questionnaire; the last part focuses on the consumption of sugar-sweetened beverages during physical activity. Results. 263 responses were collected: the sample includes 48 non-athletes and 214 athletes, of whom 149 are competitive. The study focuses on a sample of athletes who practise mainly aerobic activities, as 66.3% of competitive athletes practice triathlon, swimming or cycling. Twenty-nine people, or 11% of the total sample, stated that they had experienced episodes of respiratory apnoea during sleep. More than 80% report having had at least one caries involving permanent tooth. Conclusions. The results of the survey are in line with the prevalence reported in the literature and indicate that OSAS is still a little-known condition, despite the fact that it has been shown to be widespread. Caries is also very common in sports due to the continuous intake of sugary drinks during training.

Key words. OSAS, sleep habits, sports, athletes, oral hygiene.

Abitudini del sonno e prestazioni sportive negli atleti: uno studio di indagine

Riassunto. Introduzione. Il sonno riveste un ruolo fondamentale nella vita dell’essere umano, assolvendo a numerose funzioni fisiologiche essenziali. Tali funzioni possono essere compromesse in presenza di disturbi del sonno, tra cui la Sindrome delle Apnee Ostruttive del Sonno (OSAS). In particolare, per gli atleti, un sonno ristoratore è imprescindibile al fine di garantire prestazioni sportive ottimali. Il presente studio si propone di indagare se l’attività fisica possa svolgere un ruolo protettivo nei confronti dell’OSAS. Inoltre, si analizzano le abitudini relative al sonno e all’igiene orale degli atleti, al fine di valutarne la prevalenza dell’OSAS e della carie dentaria. Materiali e metodi. È stato somministrato un questionario a una popolazione eterogenea composta da soggetti atleti e non atleti. Il questionario era suddiviso in tre sezioni: la prima dedicata all’indagine del livello di attività fisica; la seconda finalizzata allo screening dell’OSAS mediante la Epworth Sleepiness Scale (ESS) e il questionario STOP-BANG; la terza focalizzata sul consumo di bevande zuccherate durante l’attività sportiva. Risultati. Sono stati raccolti complessivamente 263 questionari validi, di cui 48 provenienti da soggetti non atleti e 214 da atleti, tra i quali 149 risultano praticare sport a livello competitivo. Il campione oggetto di studio risulta prevalentemente composto da soggetti che praticano attività aerobiche, in quanto il 66,3% degli atleti competitivi dichiara di praticare triathlon, nuoto o ciclismo. Ventinove partecipanti (11% del campione totale) riferiscono di aver sperimentato episodi di apnea notturna. Inoltre, oltre l’80% dei rispondenti riferisce di aver sviluppato almeno una carie a carico della dentatura permanente. Conclusioni. I dati raccolti risultano coerenti con quanto riportato dalla letteratura internazionale, confermando che l’OSAS è una condizione ancora ampiamente sottodiagnosticata, nonostante la sua elevata prevalenza. Anche la carie dentaria si conferma una problematica diffusa tra gli atleti, verosimilmente correlata all’assunzione regolare di bevande zuccherate durante l’attività fisica. Tali evidenze suggeriscono la necessità di interventi di prevenzione mirati e programmi di sensibilizzazione, sia sul piano medico che odontoiatrico, all’interno delle comunità sportive.

Parole chiave. OSAS, abitudini del sonno, sport, atleti, igiene orale.

Introduction

Sleep is particularly crucial for athletes: for a long time, it has been shown that athletic performance depends on both the quality and quantity of sleep that precedes the competition.

The harmful effects of sleep deprivation on athletes vary between sports: for example, there may be increased falls, cognitive slowing, memory impairment, and decreased alertness as reported in Simpson et al. review1. In general, a lack of adequate sleep affects physical performance, which can be seen as a decline in the ability to perform maximal exercise.

It is known that athletes require more sleep than sedentary people, so 9-10 hours of mostly nocturnal sleep is ideal, compared to the 7-9 hours recommended for healthy adults2. However, athletes commonly suffer from poor sleep quality due to factors such as training intensity and timing, pre-competition nervousness and anxiety, jet lag and travel3,4.

Obstructive Sleep Apnea Syndrome (OSAS)5 is a chronic sleep disorder. It is defined by repeated episodes, more than five per hour, of partial or total upper airway obstruction (UAW) during sleep, which lead to airway obstruction (apnea) or reduction (hypopnea) despite maintenance of inspiratory efforts.

It has been estimated that athletes may be at an increased risk for certain medical conditions associated with disturbed sleep. For example, sleep-disordered breathing (SDB) has been estimated to be present in 14% of professional football players6. Dobrosielski et al. in another study reported a prevalence of SDB of 8% in a group of collegiate football players. These data underscore the importance of screening and subsequent treatment of SDB in this highly conditioned yet potentially vulnerable group of athletes7.

Given the detrimental effects that obstructive sleep apnea can have on both health and physical performance, a high index of suspicion should exist, particularly among athletes with increased body mass and large neck circumference. Suzuki H et al. reported that OSAS was identified in 86.5% of 52 rugby players, with potential contributions from the large neck circumference and characteristic facial morphology of Japanese individuals8.

In fact, the prevalence of OSAS appears to be much higher in strength athletes than in the general population, probably due to the physical factors mentioned above. A study carried out on a sample of 175 rugby players found snoring in 38% of responses and apneic events in 8% of cases. Exercise may be particularly useful for improving numerous sequelae of OSA, including cardiovascular disease, impaired glucose tolerance, and fatigue.

Furthermore, in athletes, in addition to sleep-related disorders, it has been shown that they may suffer from poor oral health caused by the frequent intake of carbohydrates in the diet, physiological changes such as decreased salivary flow and xerostomia during physical activity, as well as immunosuppression due to exercise. A review of the literature9 reports poor oral health among elite athletes: carious pathology occurred in up to 75% of athletes interviewed. Data from studies examining oral health and performance suggest that poor oral health can have a negative effect on athletes’ training and performance, as reported by those themselves; mechanisms could include pain, effects on nutrition, psychological impact and increased levels of systemic inflammation. Possible sports-related causes of poor oral health include frequent intake of carbohydrates in the diet, physiological changes such as decreased salivary flow and xerostomia during physical activity, as well as immunosuppression due to exercise.

Another review reported that the main disorders of the oral cavity, correlated with the performance of various sports that have a significant impact on the quality of life of athletes, are represented by trauma, joint disorders, alterations and/or oral pathologies, such as caries, erosions, dental discolorations and periodontal disease10.

The purpose of this study was to establish whether physical activity can play a protective role in OSAS. Athletes’ routines are analyzed, particularly in relation to sleep and oral hygiene, to investigate the prevalence of OSAS and caries, respectively.

Materials and methods

This study is based on the administration of an anonymous digital questionnaire; the questions were collected in a Google Form document, the link of which was disseminated via social media to a mixed population in terms of age, gender and level of physical activity. The study was approved by the local ethical committee with the code 541n/25. Mainly some competitive triathlon and swimming teams from the province of Padua were involved.

The questionnaire is divided into three main parts:

1) the first part of the questionnaire collects the subject’s data, in particular identifying personal data such as gender and age; furthermore, the first section investigates the subject’s level of physical activity, specifying the discipline and the weekly hours of training carried out, through mainly closed questions. Furthermore, a question was included regarding the knowledge of the OSAS pathology by the interviewed population;

2) the second part of the questionnaire includes the two screening questionnaires for OSAS, namely the Epworth Sleepiness Scale (ESS) and the STOP-BANG questionnaire;

3) the last part instead focuses on the oral hygiene habits of the individual, as well as on the consumption of sugary drinks during physical activity, the patient’s oral health status is also requested as well as investigating the possible presence of parafunctions during sleep. Finally, information is collected regarding the sleeping habits of the subjects involved, such as times and total duration of rest.

The Epworth Sleepiness Scale (ESS) is a patient-reported questionnaire that measures excessive daytime sleepiness (EDS) by assessing situational sleep propensities. Specifically, the ESS is composed of eight items that assess the likelihood of falling asleep in real-world situations, such as reading, watching television, or driving. Each item is scored from zero to 3, for a total score of zero to 24, with higher scores indicating a greater severity of EDS11.

The STOP-BANG questionnaire is a dichotomous test (yes/no) uses eight questions to investigate the main predisposing factors for OSAS, dividing patients at low and high risk of OSAS based on the scores, which range from 0 to 8. An affirmative answer to at least three questions is sufficient to correlate with a fairly high risk of OSAS12.

Finally, the data collected was divided based on the sporting level of the subjects interviewed, in particular considering the sports and non-sports groups. The sports group was further divided into competitive and non-competitive athletes. Furthermore, the data collected relating to the sports most represented in the sample were compared with each other.

Based on this subdivision, the data were analyzed with statistical methods. Categorical data were expressed as frequency and percentage, while numerical data were expressed as median and interquartile range (IQR). Categorical data were compared between groups with the Fisher test and Chi Square test, while numerical data were compared between groups with the Mann-Whitney test and the Kruskal-Wallis test. No correction for multiple testing was made because the study was exploratory and not confirmatory. All tests were 2-sided and a p-value less than 0.05 was considered statistically significant.

Results

The collected responses were sent to 255 participants, of which 148 men and 107 women with an average age of 33 years and an average BMI of 23.04 kg/m2. The data were then interpreted statistically, comparing in particular two groups, divided based on the level of physical activity. The sample includes 209 subjects who practice physical activity regularly and 46 who do not practice; among them, 147 individuals carry out sporting activities at a competitive level while 62 individuals at a non-competitive level.

The most represented sport in the data collection is triathlon, with 71 people practicing, followed by swimming (43) and cycling (17). The sports activity recorded is mainly aerobic: 66.3% of the sports sample in question performs endurance sports such as triathlon, athletics, swimming and cycling (figure 1).

The two main groups present some different characteristics, such as age and BMI: the group of competitive athletes reports an average age of 35 years and an average BMI of 22.6 kg/m2. The non-athletic group, on the other hand, appears to be younger, with an average age of 25 years and an average BMI of 22.2 kg/m2. Furthermore, the group of non-sports subjects is the only group to have a predominantly female component, with 29 women and 17 men.

Overall, 29 subjects reported that someone observed a breathing pause during their rest, equal to 11.1% of the total sample (figure 2).

The quality of their sleep reported by athletes, both competitive and non-competitive, is on average just sufficient with an average score of 6.48. Only 53.7% of the sample perceives their sleep as restful, while the remaining fraction denies it or cannot express themselves about it (figures 3, 4).

The non-athlete group has an average Epworth score of 6.5; 10 subjects out of the 46 total non-sports participants tested positive, i.e. they reported an Epworth score greater than 9. The average score on the STOP-BANG questionnaire was 1.35 and only one subject was at risk of OSAS with more than 3 answers positive. The non-athlete group sleeps on average 6.9 hours per night and 27 out of 46 subjects (58%) report being tired or drowsy during the day.

The group of competitive athletes, on the other hand, reports sleeping an average of 6.86 hours per night, with an average Epworth score of 7.6; 57 individuals out of 147 tested positive on the Epworth questionnaire with a score greater than 9. 38.7% of the sports population was therefore positive on the Epworth questionnaire regarding daytime sleepiness. 87 athletes consider themselves drowsy during the day and 26 subjects report having experienced sleep apnea, equal to 59.18% and 17.68% of the competitive sports population respectively. The average score of the STOP-BANG questionnaire stands at 1.71 positive responses, with 12 subjects out of 147 screening positive (equal to 8.16% of the competitive sports sample).

The sports population also reports going to sleep and waking up earlier than the control group: the population interviewed reports going to bed between 10pm and midnight in 71% of cases, a percentage which drops to 63% in non-athletes and rises to 76% in non-competitive athletes; vice versa, 20% of the sample usually falls asleep after midnight, a value which rises again in non-athletes to 28% and drops to 19% in competitive athletes. As regards the waking time, the range from 4 to 6 in the morning is preferred by competitive athletes, but the majority of the sample wakes up on average between 6 and 8 (75%); specifically, those who get up after 8 in the morning are 8.2% of the population, but also in this case the relative percentage drops in the competitive population (4%) and rises in the non-sports sample (13%).

Furthermore, 60.3% of the sports sample reports difficulty in resting the night before a competition. Furthermore, this difficulty is also reported by 48.5% of athletes who train in the morning (figures 5, 6).

In general, the study reports that those who practice competitive or non-competitive physical activity had more tooth decay, as well as taking more bars/gels and/or sugary drinks. In general, 77.5% of the sample performs a professional hygiene session every year and 92% of the subjects brush their teeth at least twice a day. Finally, the group of athletes consumes coffee and energy drinks in greater quantities: 82% of the athletes consume at least one coffee a day, compared to 78% of the control group.

This data becomes more significant if larger doses of caffeine are considered: 22% of the normal population consumes more than three coffees a day, compared to 40% of competitive athletes. Energy drinks are used more than twice a month by 7% of athletes, while none of the control group reported such a high frequency of use (figures 7, 8).

Despite good oral hygiene habits, more than 70% of the total sample reported having had at least one cavity of a permanent tooth. Furthermore, 17.3% of the total lost a tooth due to tooth decay (figure 9).

The questionnaire also investigated the presence of parafunctions such as clenching and nocturnal grinding: it emerged that 33% of the total sample reported clenching their teeth during sleep, without particular differences between the groups. The percentage of people suffering from headaches is also 37%, with a higher prevalence in the non-sports group (46%) than in the “athletes” group (35%).

A final interesting fact concerns the knowledge of OSAS in the general population: only 20% of the individuals interviewed know the pathology and the related consequences (figure 10).

Discussion

The data reported highlight how athletes are more subjected to stress and difficulty falling asleep, as reported by various studies in the literature13,14. According to the recommendations of the National Sleep Foundation, an athlete should sleep on average 9-10 hours to obtain restful rest, compared to the 7-9 hours slept by a common adult2. The present study, however, does not report significant differences in the hours of sleep slept by the two groups: almost 2 out of 3 people of the total sample (71%) sleep 6-7 hours per night, and this figure remains almost unchanged in the individual groups; similarly, around 20% of athletes and non-athletes alike sleep 8-9 hours. Furthermore, the sports population reports earlier times of waking up and falling asleep, probably due to the scheduling of competitions and training sessions which forces them to have an earlier pace of life. Sporty individuals wake up after 8.00 in the morning in 10% fewer cases than the control group, and in the same percentage difference they fall asleep after midnight.

However, the quality of sleep perceived by athletes turns out to be better, given that the sports population reports experiencing restful sleep in 59.7% of cases, compared to 43.5% of non-athletes. This contrast can be explained by some studies13 which report a better quality of sleep perceived by those who carry out physical activity regularly.

Another complication encountered by athletes can be found in the context of the night before training sessions or a competition: according to the present study this is the case for one in two athletes who train in the morning; as regards the evening before a race, the obstacle to a restful sleep is encountered in 60.3% of the total sports sample. Several studies investigate this phenomenon, such as the case of Lastella et al.15, Gupta et al.16 and Leeder et al.14 in the previously cited articles; furthermore, Juliff et al.17 also report a similar phenomenon applied on a large scale on 283 Australian elite athletes, who were asked the causes of their bad sleep: in particular the athletes had problems falling asleep (82.1%) due to the thought of the race to be played the following day (83.5%) and nervousness (43.8%).

There are figures such as the sleep coach, particular mental coaches dedicated precisely to the management of pre-race anxiety. Juliff et al.17 still report that more than 59.1% of athletes involved in team sports do not have a strategy to overcome difficulties falling asleep, compared to 32.7% of athletes in individual sports who instead use techniques such as meditation or reading.

With regard to both screening questionnaires we see how the general population in fact reports an Epworth score of 6.5, compared to the average score of athletes which instead stands at 7.6; furthermore, the test positivity is respectively 21.7% (10 out of 46 subjects) and 38.7% (57 out of 147 athletes). On this analysis, greater daytime sleepiness could be attributed to physical activity and, given that the Epworth is an index whose positivity often correlates with the presence of OSAS, in the same way a greater incidence of apnea in athletes could be associated. While this may be true, as demonstrated by the study by Duncan et al. referring to a high prevalence of sleep disorders in professional rugby athletes18, on the other hand this data must certainly be considered in the context of the present study.

In the analysis just cited, athletes practicing contact sports are therefore BMI and neck circumference greater than the threshold for OSAS risk; therefore, a higher incidence of sport-related pathology is plausible. One of the particularities of the present study refers to the large part of the sports sample who instead practices resistance sports which are associated with excellent physical shape, 66.3% being practitioners of triathlon, athletics, swimming or cycling, for which the previous correlation of the Duncan study is not applicable.

The same considerations are equally true regarding the STOP-BANG questionnaire, given the 2.17% positive result of the non-sports sample compared to 12.24% of the athletes.

The most relevant data, however, is the general one, which allows an epidemiological investigation on a sample of 255 healthy individuals, on average young (total average age of 33 years) and in good physical condition: 58% of the total are in possession of a medical certificate competitive certificate issued annually after carrying out various tests. Therefore, despite the good state of health and physical fitness involved, 29 out of 255 individuals (11.1%) report that someone close to them has perceived their breathing pause during sleep. Furthermore, 67 individuals out of 255 tested positive on the Epworth Sleepiness Scale regarding daytime sleepiness, equal to 26.27% of the total sample; again, 12 individuals out of 255 (4.7%) are positive on the STOP-BANG questionnaire, correlated with a moderate risk of OSAS. This data are indicative, for example, if placed in the context of the screening protocol for Sleep Apnea Syndrome applied in the Dental Clinic of Padua, which involves subjecting all patients, during the first orthodontic visit, to the attached Epworth questionnaire the compilation of the general medical history; all patients with a score greater than 9 are screened positive and are by default considered as “diagnostic suspect”, which is then investigated in more depth with a home polysomnography. It follows that 1 in 4 subjects in the present study, although in good physical health, should be subjected to an in-depth diagnostic examination via polysomnography: from this perspective, therefore, it begins to represent a significant number of positive cases. Several articles report how the Epworth test measures daytime sleepiness subjectively19, and it is therefore strongly influenced by the patient’s perception of himself and by the habits applied during the day as reported in their study by Guimarães et al.20 who define the Epworth Sleepiness Scale as “an underrated subjective scale”. It is therefore reasonable to assume that also in the case of our study the Epworth score is limited, and that therefore the population at risk is potentially larger.

The fact that more than 1 in 10 people report that someone has perceived a breathing pause during sleep is also indicative, especially considering that to obtain this data the presence of a bed partner is required and that this partner is able to perceive the phenomenon.

As regards the prevalence of caries, however, the present study is in line with the data reported in the literature. The general prevalence of at least one permanent tooth cavity stands at 70%, but the comparison between populations is indicative: the percentage of those who have had more than 10 cavities is 1% in non-athletes and 18% among athletes agonists. Among competitive athletes, more than 20% have lost a tooth due to decay, i.e. 1 athlete in 5, compared to 10% of the control population; it follows that sports athletes have double the risk of losing teeth due to decay.

Ashley et al.9 report a spread of carious pathology in 75% of the sports population; Furthermore, it is reported that poor oral health can negatively impact the training and performance of athletes due to pain, effects on nutrition and increased levels of systemic inflammation.

The causes of tooth decay are to be found in physiological changes that can occur during sports performance, such as the decrease in salivary flow and xerostomia, as well as a relative immunosuppression caused by physical exercise; furthermore, a main role is also played by the frequent intake of carbohydrates during physical activity, especially in relation to athletes endurance. Even more so due to the fact that over 60% of the present study refers to endurance sports athletes, the data collected fully confirm this hypothesis: those who practice competitive or non-competitive physical activity have had more tooth decay, in addition to taking more bars /gels and/or sugary drinks. There are other studies in the literature that confirm high risk for developing caries and erosion caused by diet of athletes21,22.

The oral hygiene habits of the sample are nevertheless excellent, given that 77.5% of the sample performs a professional hygiene session every year and 92% of the subjects brush their teeth at least twice a day.

Finally, it is interesting that only 20% of the total sample reported having in-depth knowledge of Sleep Apnea Syndrome and the related consequences; this value would probably be lower, given that some medical professionals, including most dentists, are known to be included in the sample. It is therefore reasonable to think that this percentage may be overestimated compared to the population without medical knowledge and that, therefore, OSAS is a very little known disorder at a general level in the community.

Future insights and developments

The evolution of the current study could involve the diagnosis of OSAS through instrumental examination, i.e. polysomnography. The prevalence of OSAS in the world of endurance sports is little noted in the literature, but it could be an interesting comparison with the numerous studies that instead concern contact sports.

Sleep may exert different effects on different sports as a result of the differential effect on the specific tasks involved. While data relating to sleep and performance on endurance, reaction time and accuracy are consistent, the effects on strength, sprint and power are less clear, with obvious implications for performance in sports that significantly incorporate these elements. Furthermore, although the relationship between impaired sleep and decreased performance is considerable, the underlying mechanisms are poorly defined. Future research could aim to identify the biomechanical, psychological and physiological mechanisms that mediate the influence of sleep on performance in athletes of different sports.

The impact of disturbed sleep could be measured directly on the performance of athletes through specific tests, such as threshold tests performed in cycling or athletics; such data could then be correlated to polysomnographic indices, to highlight how the alteration of breathing, blood pressure and heart rate caused by apnea can directly affect the parameters detected by sports tests, such as gas exchange volumes and resistance developed during effort.

Conclusions

Athletes consistently demonstrate insufficient sleep and poor sleep quality caused by a number of unique barriers including training and competition schedules, travel, training load fluctuations, anxiety and stress associated with sporting events, and the academic demands of younger athletes. Longitudinal monitoring of training load, sleep, fatigue, stress and mood can help monitor improvements in sleep, well-being and performance after interventions, as well as identify those at risk. Proper sleep environments and schedule could improve sleep quality.

OSAS is a very widespread disease but, in the majority of the common population, still unknown. The dentist should identify the patient’s symptoms early, make a correct diagnosis for adequate treatment. Furthermore, since the carious pathology is very widespread among athletes, it would be advisable to provide frequent oral hygiene reminders and intercept small lesions in the oral cavity. It is therefore essential to raise awareness about this, both at a healthcare level and in schools, so that the diagnosis can be made in a timely manner, improving quality of life and reducing the costs of the National Health System due to the related consequences.

Conflicts of interest. The authors declare that there is no conflict of interest.

Authors contributions. All the authors contributed equally to the manuscript. All authors read and approved the final version of the manuscript.

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