Research Review By Christopher Howard

Date Posted:

November 2010

Study Title:

High Exercise Levels are Related to Favorable Sleep Patterns and Psychological Functioning in Adolescents: A Comparison of Athletes and Controls

Authors:

Brand S, Gerber M, Beck J et al.

Author's Affiliations:

Psychiatric Hospital of the University of Basel, Depression and Sleep Research Unit, Basel, Switzerland; Institute of Exercise and Health Sciences, University of Basel, Basel, Switzerland; Psychiatric Out-Patient Clinic of the University of Basel, Basel, Switzerland

Publication Information:

Journal of Adolescent Health 2010; 46: 133–141.

Background Information:

Adolescents require 9 to 10 hours of sleep per night (1), however for most adolescents, sleep time decreases to 6.5-8.5 hours during school nights due to delayed bed times. As a result, daytime sleepiness and insomnia symptoms (2) are common among teenagers, especially female teens (3). In addition, poor sleep affects quality of life, routine daily functioning (4), and academic performance (5).

For many teens, getting sufficient sleep isn’t a perceived option and coping with poor sleep is more likely. This often results in the use of substances to induce sleep or to reduce sleepiness (caffeine). However, many experts see exercise as an effective and inexpensive means of preventing and reducing sleep problems (6).

There are two main theories on how and why exercise has a positive impact on sleep. The first theory postulates that physical activity results in physiological changes that help regulate sleep. In addition, acute exercise seems to reduce daytime sleepiness and stabilize the circadian rhythm.

The second theory states that physical activity may improve sleep through general psychological improvements. Exercise is associated with reduced symptoms of depression and anxiety, and increased self-esteem.

While there is abundant evidence that physical activity results in improved psychosocial and physiological characteristics, there is not an abundance of research regarding sleep. The goal of this study, therefore, was to examine the relationships between exercise and sleep among adolescent athletes and controls.

Pertinent Results:

Sleep Patterns in Athletes and Controls:
  • Compared with controls, athletes had higher scores for mood (morning and evening), sleep quality, and restoring sleep.
  • Athletes had quicker sleep onset, fewer awakenings after sleep onset, higher concentration levels during the day, and lower tiredness during the day.
  • There was no difference between groups with regards to total sleep time.
Psychological Functioning in Athletes and Controls:
  • Athletes had lower scores for depressive symptoms and trait anxiety than control subjects.
  • There was no significant difference for state anxiety and stress between controls and athletes.
  • Athletes had more favorable scores on all dimensions of sleep-related personality traits.
Sleep Patterns and Psychological Functioning (separated by gender):
  • Female participants reported more awakenings after sleep onset and lower scores for restoring sleep than male subjects. For all other sleep dimensions, there were no statistically significant differences by gender.
  • Significant group x gender interactions revealed that females’ sleep quality and mood (evening) remained stable between the groups, whereas the lowest scores were observed in the male control group.
  • Female participants had higher scores for depressive symptoms, stress and trait anxiety, but less state anxiety than male participants. Females reported more assertive behavior, less physical arousal, less self-perception of body sensations, and a lower sleep quality.
  • Group x gender interactions showed the following pattern of results: male athletes had higher (i.e., ‘‘better’’) scores for self-confidence, physical arousal, sleep quality, focusing, and rumination than male controls, whereas female athletes and female controls did not differ from one another in these respects.
Determinants of Sleep Quality: Multiple Regression Analyses:
  • Regression analysis was used to predict sleep quality, tiredness and concentration during the day as a function of group, gender, psychological functioning, and level of exercise.
  • Sleep quality was predicted by being an athlete and increased physical arousal but by lower stress, state anxiety, and rumination.
  • Tiredness during the day was predicted by being a participant in the control group, increased stress, increased mental arousal, and an unfavorable attitude toward life.
  • Concentration during the day was predicted by being an athlete, low trait anxiety, and low stress, but also by greater self-confidence, aggressive behavior, mental arousal, and decreased rumination.

Clinical Application & Conclusions:

The key findings of this study are that adolescent athletes reported better sleep patterns and better psychological functioning than controls, and that adolescent males with low exercise levels were at increased risk for poor sleep and psychological functioning. Based on the results of this study, adolescent health and wellness programs should promote regular exercise and sport participation.

Study Methods:

Subjects:
  • A total of 434 adolescents (age: mean 17.2 years) took part in the study. Of these, 258 were athletes (139 females and 119 males). In addition, there were 176 controls (139 females 37 males).
Procedure:
  • Adolescent athletes were recruited from 'Swiss Olympic Classes' in the German speaking part of Switzerland. 'Swiss Olympic Class' are provided for adolescent athletes who exhibit high national performance, although not necessarily an international performance.
  • Controls were recruited in the Cantons of Basel and Basel Land, two districts of the German-speaking northwestern part of Switzerland.
  • Participants completed several psychological and sleep-related questionnaires as described below, and they kept a sleep log for 7 consecutive days, covering 5 school days and 2 off-school days.
Materials:
  • Exercise participation: The amount of time the adolescents spent exercising was determined via a self-administered, 7-day log. Students were asked to record duration of exercise resulting from either (1) participation in practice that resulted in increased heart rate and perspiration, or (2) participation in sports (aka games). Results were as follows: female athletes (mean 17.09 hours), male athletes (mean 18.39 hours), female controls (mean 4.68 hours), male controls (mean 4.73 hours).
  • Sleep: The sleep log was based on the Pittsburgh Sleep Quality Index. All participants were asked to fill out the log twice per day for 7 days, both in the morning and evening. In the evening, participants answered questions on an eight-point visual analogue scale regarding tiredness during the day, concentration during the day, and mood at bed time. In the morning, participants answered questions regarding mood on waking, sleep quality, and feeling of being restored. Additionally, sleep onset latency (in minutes), number of awakenings, and total sleep time (in hours and minutes) were reported.
Psychological Functioning:
  • All participants completed questionnaires related to depression, state-trait-anxiety, everyday stress, and sleep-related personality traits. The dimensions assessed with these four questionnaires were summarized as psychological functioning, in which high psychological functioning indicated low depressive and anxiety symptoms, low everyday stress, and favorable personality traits.
  • Depression Scale: The Depression Scale consists of 16 items and asks about typical depression-related symptoms such as depressed mood, lack of satisfying social interaction and leisure activities, hopelessness, and sleep complaints. The higher the overall score, the more pronounced the depressive symptoms.
  • State-Trait-Anxiety Inventory: The State-Trait Anxiety Inventory asks about current (state) and chronic (trait) anxiety symptoms. Higher mean scores reflect greater state or trait anxiety.
  • Everyday stress: A self-administered questionnaire asking about stress was applied. Higher scores reflect a greater amount of stress in every day life.
  • Sleep-related personality traits: Participants also completed a sleep-related personality questionnaire, specifically designed to assess personality traits of patients with sleep complaints. The FEPS-I questionnaire consists of 64 items describing six sleep-related personality traits and subjective sleep quality. Higher scores reflect more favorable qualities (e.g., subjective sleep quality: regenerative, undisturbed, unimpaired). The FEPS-II questionnaire consists of 23 items with the dimensions of ‘‘Focusing’’ - the tendency for a person to think constantly about their difficulties in getting to sleep, remaining asleep, waking up early in the morning and/or suffering from increased daytime sleepiness and ‘‘Rumination’’ - the tendency for a person to think continuously about and feel preoccupied with unresolved problems.

Study Strengths / Weaknesses:

Something that immediately stuck out in this study was that even the control group was participating in roughly 5 hours per week of exercise, which is probably more than most American adolescents. Therefore, although the controls in this study exhibited unfavorable characteristics compared to the athletes, it could be expected that American adolescents would fare much worse. More research needs to be done in this area. Studies examining those who exercise versus those who are completely sedentary (as many teens are) are needed.

Overall, this study did an excellent job of examining the differenced between athletes and controls with regards to sleep differences. The rather large sample size and thorough data collection help increase the significance of the results of this study.

Additional References:

  • Mercer PW, Merritt SL, Cowell JM. Differences in reported sleep need among adolescents. J Adolesc Health 1998;23:259–63.
  • Millman RP, Working Group on Sleepiness in Adolescents/Young Adults; and AAP Committee on Adolescence. Excessive sleepiness in adolescents and young adults: Causes, consequences, and treatment strategies. Pediatrics 2005;115:1774–86.
  • Moline ML, Broch L, Zak R, et al. Sleep in women across the life cycle from adulthood through menopause. Sleep Med Rev 2003;7:155–77.
  • Banks S, Dinges DF. Behavioral and physiological consequences of sleep restriction. J Clin Sleep Med 2007;3:519–28.
  • Curcio G, Ferrara M, De Gennaro L. Sleep loss, learning capacity and academic performance. Sleep Med Rev 2006;10:323–37.
  • Vuori I, Urponen H, Hasan J, et al. Epidemiology of exercise effects on sleep. Acta Physiol Scand 1988;574(Suppl):3–7.