Eirunn Thun

Sleep, circadian rhythms, and athletic performance

Sleep deprivation and time of day are both known to influence performance. A growing body of research has focused on how sleep and circadian rhythms impact athletic performance. This review provides a systematic overview of this research. We searched three different databases for articles on these issues and inspected relevant reference lists. In all, 113 articles met our inclusion criteria. The most robust result is that athletic performance seems to be best in the evening around the time when the core body temperature typically is at its peak. Sleep deprivation was negatively associated with performance whereas sleep extension seems to improve performance. The effects of desynchronization of circadian rhythms depend on the local time at which performance occurs. The review includes a discussion of differences regarding types of skills involved as well as methodological issues.

Night work and symptoms of anxiety and depression among nurses: A longitudinal study

Over the last few decades, night work has been found to be associated with negative somatic consequences; however, there is less knowledge about its impact on mental health. In a sample of 633 Norwegian nurses, we investigated by means of latent growth curve modelling whether different work schedules predicted differences in baseline values of anxiety and depressive symptoms, and trajectories of these over a two-year span. All participants completed the Hospital Anxiety and Depression Scale as part of a larger survey conducted during the winters of 2009, 2010 and 2011. The results revealed that night workers and nurses who changed from day work to night work during the study period did not differ from day workers either in terms of baseline symptoms of anxiety or depression, or in terms of trajectories of these symptoms. However, nurses who changed from night work to day work reported a significant decrease in symptoms of both anxiety and depression over time compared to day workers. Furthermore, supporting previous work, languidity was related to higher anxiety and depression and hardiness to lower levels of those symptoms. Possible mechanisms underlying the results are discussed.

A Comparative Study of Sleep and Mood Between Young Elite Athletes and Age-Matched Controls

BACKGROUND Sleep and mood have seldom been compared between elite athletes and nonelite athletes, although potential differences suggest that physical activity may affect these parameters. This study aims to explore whether adolescent elite athletes differ from controls in terms of sleep, positive affect (PA) and negative affect (NA). METHODS Forty-eight elite athletes and 26 controls participating in organized and nonorganized sport completed a questionnaire, and a 7-day sleep diary. RESULTS On school days, the athletes and the controls who participated in organized and nonorganized sport differed in bedtime (22:46, 23:14, 23:42, P < .01), sleep onset (23:03, 23:27, 00:12, P < .01), and total sleep time (7:52, 8:00, 6:50, P < 01). During weekend, the athletes, the controls who participated in organized and nonorganized sport differed in bedtime (23:30, 00:04, 00:49, P < .01), sleep onset (23.42, 00:18, 01:13, P < .01), rise time (9:15, 9:47, 10:55, P < .01), sleep efficiency (95.0%, 94.2%, 90.0%, P < 05), and sleep onset latency (11.8, 18.0, 28.0 minutes, P < .01). Furthermore, the athletes reported less social jetlag (0:53) and higher score for PA (34.3) compared with the controls who participated in nonorganized sport (jetlag: 1:25, P < .05, PA: 29.8, P < .05). CONCLUSIONS An almost dose-response association was found between weekly training hours, sleep, social jetlag and mood in adolescents.

Trajectories of sleepiness and insomnia symptoms in Norwegian nurses with and without night work and rotational work

ABSTRACT Numerous cross-sectional studies report high prevalence rates of sleepiness and insomnia in shift workers, but few longitudinal studies exist. We investigated trajectories of sleepiness and insomnia symptoms in a sample of Norwegian nurses across four measurements, spanning a total of four years (sleepiness) and five years (insomnia). The participants completed the Epworth Sleepiness Scale and the Bergen Insomnia Scale at each measurement instance. Latent growth curve models were used to analyse the data. Separate models examined night work (night work, entering and leaving night work) and rotational work (rotational work, entering and leaving rotational work) as predictors for trajectories of sleepiness and insomnia symptoms, respectively. Baseline values of sleepiness and insomnia were higher among rotational shift workers than among workers with fixed shifts (day or night). The results showed that night work throughout the period and entering night work during the period were not associated with different trajectories of sleepiness or insomnia symptoms, compared to not having night work. The same results were found for rotational work and entering rotational work, compared to not having rotational work. Leaving night work and leaving rotational work were associated with a decrease in sleepiness and insomnia symptoms, compared to staying in such work.

Restricted use of electronic media, sleep, performance, and mood in high school athletes—a randomized trial

OBJECTIVES The study aims to evaluate whether 4 weeks with restricted use of electronic media after 22:00 affects sleep, athletic performance, cognitive performance, and mood in high school athletes. METHODS Eighty-five athletes were randomized to either an intervention group (n = 44), who was instructed to not use any electronic media after 22:00, or a control condition (n = 41), where they could act as they preferred in terms of media use. Primary outcomes were sleep habits measured with a sleep diary. Secondary outcomes were (a) physical performance measured with a set of standardized tests (beep test, 20-m linear sprint, chin-up test, hanging sit-ups test, counter movement jump and sit-n-reach test); (b) cognitive performance (response time and response accuracy); and (c) positive and negative affect. Differences between groups were tested with mixed between-within subject analyses of variance. RESULTS AND CONCLUSIONS Thirty-five and 40 of the athletes in the intervention and control group, respectively, completed the study. Results showed that restricted use of electronic media after 22:00 did not improve sleep habits, athletic performance, cognitive performance, or mood in a group of high school top athletes with already good sleep habits. However, these findings give us knowledge about sleep habits and performance in this population that is of importance when designing future studies.

The Effects of Sleep Deprivation on Soccer Skills

Many athletes sleep poorly due to stress, travel, and competition anxiety. In the present study, we investigated the effects of sleep deprivation on soccer skills (juggling, dribbling, ball control, continuous kicking, 20 and 40 m sprint, and 30 m sprint with changes of direction). In all, 19 male junior soccer players (14–19 years old) were recruited and participated in a cross-balanced experimental study comprising two conditions; habitual sleep and 24 hours sleep deprivation. In both conditions, testing took place between 8 a.m. and 10 a.m. Order of tests was counterbalanced. Each test was conducted once or twice in a sequence repeated three times. The results revealed a negative effect of sleep deprivation on the continuous kicking test. On one test, 30 meter sprint with directional changes, a significant condition × test repetition interaction was found, indicating a steeper learning curve in the sleep deprived condition from Test 1 to Test 2 and a steeper learning curve in the rested condition from Test 2 to Test 3. The results are discussed in terms of limitations and strengths, and recommendations for future studies are outlined.

Predictive Value of the SF-12 for Sickness Absence Because of Mental, Musculoskeletal, and Other Somatic Disorders.

Objective: To investigate the predictive value of the 12-item short form (SF-12) for long-term sickness absence (LTSA) because of mental, musculoskeletal, and other somatic disorders. Methods: In this cohort study with 2-year follow-up of 1381 nurses, baseline SF-12 scores were analyzed against registered mental, musculoskeletal, and other somatic LTSA during follow-up by logistic regression models. Results: The SF-12 dimensions, general health, vitality, emotional role limitations, mental health, and social functioning, predicted mental LTSA. Physical functioning, bodily pain, and vitality predicted musculoskeletal LTSA, and physical role limitations, bodily pain, general health, and social functioning predicted other somatic LTSA. Positive predictive values were low, and negative predictive values were high. Conclusions: Different SF-12 dimensions predicted mental, musculoskeletal, and other somatic LTSA but did not identify nurses at high risk of mental, musculoskeletal, and other somatic LTSA.