Sleeping Beauties: An Examination of Quality and Quantity of Sleep in Professional Ballet Dancers / Reena Bhattacharjee (2021)

Sleep is one of the most constant and essential universal aspects of human existence. When considering the extreme physical and mental requirements made of dancers during their career, sleep becomes even more important. The number of lifestyle and work-specific factors that are likely to disrupt the circadian alignment of company ballet dancers places yet more importance on awareness of how sleep impacts on, and is impacted by, other aspects of wellbeing. How sleep relates to mood states has not been explored in dancers at all, although such research has been extensively undertaken in other athletes. Similarly, explorations into how sleep and mood interact differently through different intensities of work has been demonstrated in athletic populations, but research in dancers is extremely limited. Current research suggests that sleep indices and mood states worsen in line with work intensity (i.e. in the lead up to a performance), but do not examine how indices change from workdays to non-workdays, irrespective of intensity or phase of work (training/rehearsal/performance). Research into overtraining (a common issue in dancing populations) repeatedly identifies poor sleep indices as one of the first warning signs, and subjective reports of poor sleep quality and quantity in dancers have been established. This study was conducted to observe and examine how sleep variables and mood states interact, and how these variables and interactions change in relation to changing work intensities. The intention of this study was to collect very in-depth data on a small number of participants, to allow for detailed and comprehensive narrative analysis to take place, in order to inform the design of further and bigger studies on dancing populations. Four professional company-employed ballet dancers wore wristwatch actigraphs and completed daily Abbreviated Profile of Mood States (APOMS) questionnaires for a period of approximately four months. This period was divided into three distinct phases of work; training (daily company class only), rehearsal (company class and repertoire rehearsals) and performance (much longer days including daily class, rehearsals and filming of prepared work). Sleep quantity data collected included total sleep time 3 (TST), time in bed (TIB) and bed and wake times, and quality indices collected and calculated were sleep efficiency (SE) and number of awakenings per nocturnal sleep. Data were analysed by comparing results from phase to phase, and were also categorised into workdays, non-workdays, pre- workdays and pre- non-workdays. Data were explored to identify trends and patterns within participants, from phase to phase, by type of day, and comparisons were also made across the cohort. The results clearly showed that (1) patterns exist between sleep and mood states, (2) changes in work intensity impact both sleep quantity and quality, as well as mood, and (3) that sleep quantity, quality, and mood states all change in relation to type of day. The nature of the relationship between the variables could not be defined, but the results provide a strong basis and justification for further research into the interaction between the variables, and the importance of sleep for dancers.