The aim of this study was to assess subjective sleep quality and daytime sleepiness in German female youth national ice hockey athletes at the start and end of a TC immediately preceding the World Championship Division IA tournament. Results imply a significant increase in subjectively perceived sleep quality over the course of the TC. Based on the results of the component score analyses, this increase appears to be due to increased sleep duration over the course of the TC rather than due to an increase in subjective sleep quality. There was no statistically significant trend for the sample’s daytime sleepiness. Descriptively, there was a reduction in daytime sleepiness from the start of the TC to the end. Thus, a pre-tournament TC seems to be an effective and beneficial measure to ensure an improvement in sleep quality and decline of sleepiness, as a prerequisite for performance readiness in an upcoming tournament. The reduction in training intensity during the TC and the temporary reduction of the double burden of school and training due to the Christmas holiday period might have been major influencing factors in this improvement of sleep quality and daytime sleepiness [25]. The implementation of guided relaxation techniques before bedtime, the absence of smartphone use before going to sleep, and scheduled bedtimes, which all constitute sleep hygiene interventions [10], probably promoted more restful sleep. Anecdotal reports from athletes indicated a beneficial effect of relaxation techniques, which should be systematically assessed in future studies on the effects of sleep hygiene interventions. TC conditions of short distances between the hotel and ice stadium, having meals together, and the common bedtime routine potentially promoted stress reduction and (social) recovery, which, in turn, positively affected sleep and sleepiness [17, 22]. For some athletes the opposite trend was observed, as they showed an increase in daytime sleepiness or a decrease in sleep quality from pre- to post-TC measurements. The unfamiliar sleep environment of the hotel, the fact of sharing bedrooms with a teammate, and different sleeping conditions might have interfered with sleep in these players more than for others [18], and/or they may be more sensitive or already slightly disturbed sleepers. Performance pressure and nervousness due to the nomination process and the upcoming tournament constitute other possible factors that might have contributed to the impairment of sleep quality and daytime sleepiness in some players. These individual deviations from the average trend in the team underline the individuality of sleep and sleeping behavior, requiring an individual assessment and evaluation of sleep [14, 30].

Comparison with other studies that examined sleep in athletes shows that the average PSQI and ESS scores of the sample were quite similar to those reported in previous studies on male and female winter Canadian national team athletes, highly trained team sport athletes, and collegiate student athletes (e.g., female student athletes, female field hockey players) [4, 21, 29]. The sample’s mean scores and their decrease over time were very similar to those reported for the men’s junior national team [14]. In case of the male ice hockey players, however, there were no interventions addressing sleeping conditions as for the current sample of female youth athletes. Like the men’s youth ice hockey team, the German team won the tournament, although one quarter of the team showed excessive daytime sleepiness and poor sleep quality was found in a third of all players at the end of the TC. The cause for these striking values could be a lack of sleep quality characteristics and sleep duration. Whether further improvement of performance could have been achieved by greater improvement in sleep parameters or whether a temporal neglect of sleep quality during tournament phases is tolerable needs to be specifically examined [14]. Follow-up assessments including frequent measurements covering season and off-season phases as well as pre- and post-competition periods would provide a more comprehensive view of players’ sleep and daytime sleepiness. This would in turn enable a differentiation between temporary sleepiness and impaired sleep quality during (preparation for) championship periods and continuous and long-lasting disturbed sleep going beyond tournament phases.

Regarding position-specific differences, the lower sleep quality in F compared to D and G at both measurements might be explainable by their higher performance demands causing potentially stronger interference with sleep quality due to higher levels of post-practice or post-competition muscle soreness or pain [12], and possibly due to a higher level of responsibility. As with sleep quality, the daytime sleepiness of F was slightly higher at the first measurement. The development of daytime sleepiness of D and G over time, however, was contrary to the development observed in F and the whole team, as it increased at the end of the TC. Possibly, the D and G experienced training sessions or test games during the TC as more intense and demanding than the group of F, which may have caused an increase in daytime sleepiness and fatigue but did not interfere with sleep quality. The possible effects of performance demands and training intensity on sleep should be investigated in more detail in future research, considering and integrating objective training parameters. The chosen group formation of building the DG out of D and G might have been another influencing factor, as the demands of G and D differ [13]. Differences between player positions should be assessed in a larger sample of female athletes, including young and adult athletes and a sufficient number of players in all three positions. Furthermore, differences in performance demands might be reflected in different recovery patterns and needs, rather than having a direct effect on sleep. Therefore, future research on the interactions between performance demands, recovery, and sleep is required.

Even though the PSQI and ESS have been frequently applied in sporting contexts, future studies should additionally include sport-specific questionnaires such as the Athlete Sleep Behavior Questionnaire [11] considering athlete-specific sleep challenges [14]. The ESS was validated for sleep apnea patients and not for young athletes, which should be considered concerning the psychometric criteria of the questionnaire and its suitability [15]. The questionnaires were chosen for comparison purposes and due to being time effective and capturing the subjective perception of sleep while affecting athletes’ sleeping conditions as little as possible. However, data do not allow statements on sleep stages, sleep parameters, or the diagnosis of sleep disorders [30]. The assessment served as a pre-screening to identify potentially vulnerable athletes for whom objective methods including polysomnography and actigraphy would then need to be applied to examine sleep architecture and sleep parameters in more detail. Significant parameters such as subjective and objective information on sleep duration, further assessments of sleep quality using other sleep questionnaires, and information on other relevant factors such as chronotype would have been valuable additions. The questionnaire-based assessment should be kept in mind when interpreting the results, as should the small and selective sample, which might be one factor contributing to the low test–retest reliability of the PSQI. Furthermore, the PSQI refers to the period of the past month; the assessment, however, was conducted within 1 week, which is rather short to include significant changes. Thus, time-specific instructions for the PSQI should be applied to comparable studies using this questionnaire. Results are based on group means which do not provide information on individual players’ sleep and reaction to tournament conditions and applied sleep hygiene measures, which should always be examined in view of the high interindividual variability in athletes’ sleep and recovery [14, 17].

This study is of high practical relevance due to data collection during the preparation camp of the IIHF U18 Women’s World Championship Division IA tournament. This study underscores the need for monitoring and screening athletes’ sleep during special and decisive sports events, in order to identify a possible need for intervention as early as possible to prevent serious and career-affecting consequences for athletes’ performance capability and well-being. Subjectively perceived sleep quality and daytime sleepiness were assessed using the PSQI and the ESS, which should be complemented by additional parameters relevant for the evaluation of sleep. Generally, sleep management strategies and sleep education should be implemented in elite and high-performance sports to raise athletes’ and coaches’ awareness of the importance of adequate sleep and sleep management.