LWL | The Impact of Daytime Physical Activity During on Sleep Quality: A Comparative Study Using WHOOP Data

By Rashed Alozaibi 

Research Question: 

To what extent does engaging in a week of soccer affect the sleep quality of a 15-year-old male,  as measured by total sleep time, deep sleep duration, and sleep efficiency, compared to a week  without physical activity, measured by a WHOOP wrist band? 

Abstract: 

The aim of this study investigates the impact of daytime physical activity on sleep quality,  specifically using the findings of the role that soccer plays in influencing sleep quality. Data will  be collected using a WHOOP wrist band, comparing sleep quality over two weeks: For one week  I will be playing soccer on Monday, Wednesday, and Thursday engaged in soccer. And one week  without physical activity. The results will show if playing soccer enhances sleep duration, deep  sleep duration and sleep efficiency. The results of this research will suggest that physical  activity may potentially promote sleep, especially for people with sleep difficulties. 

Introduction: 

According to (The National Sleep foundation 2023) it is stated how quality sleep is important as  it effects memory consolidation, learning, and problem-solving, and poor sleep is associated  with various negative outcomes, including impaired concentration, mood disorders, and  increased risk of chronic health issues such as cardiovascular disease (Cardiovascular  Disease, 2022). Sleep plays a much more important role in the adolescent, as it has influence  on growth, development and academic performance. The CDC (CDC 2022) says that most  people (specifically teenagers) need about eight to ten hours of sleep per night, but many don't  get that much, and the reasons often have to do with academics, social life and irregular sleep  routines. 

For years, the health benefits of physical activity have been very well known, one of them being  that it helps promote better sleep quality. Improvements in sleep have been shown after people  perform aerobic exercises throughout the day, some of these improvements include sleep  onset, sleep duration, and sleep efficiency (Smith, 2021). The Sleep Foundation. (Sleep  Foundation 2021) have stated that it is believed that physical activity helps increase the body’s  production of adenosine, a compound that promotes sleepiness, and also lowers the levels of a  hormone called cortisol, which although not a direct disruptor of sleep, can cause other types  of sleep deprivation such as stress. Furthermore, regular exercise plays a role in keeping the  circadian rhythm stable, which is the body’s internal clock, responsible for regulating sleep and  wake cycles, in a healthy and high-functioning state (American Academy of Sleep Medicine,  2022). 

Despite this link between exercise and better sleep, most literature has been directed to  generalized populations or adults. Very few studies to our knowledge have examined the effect  of daytime physical activity on adolescents' sleep quality specifically using wearable  technology. For this reason, I will consistently participate in soccer three times for one week then measuring my average time asleep, and for the other week I will not be participating in any  physical activity. 

Literature Review: 

Several studies have proved that physical activity, specifically, aerobics exercise, leads to better  quality sleep. Regular exercise may help a person fall asleep faster, have a longer sleep  duration, and sleep through earlier and longer stages of sleep (American Academy of Sleep  Medicine, 2022). According to the Sleep Foundation (Sleep Foundation, 2021) a study shows  that moderate intensity of aerobic exercises (jogging, swimming) improves sleep onset and  enhance the amount of restorative sleep, especially the amount of slow wave sleep (deep  sleep), which is essential for physical recovery and mental regeneration. By its very nature,  these types of activities put intense physical effort on your body, which may help your body to  relax, go to sleep more naturally and sleep more efficiently (Smith, 2021). 

Recently, the widely popular WHOOP wristband has been an invaluable tool  to help sleep research. Continuous, non-intrusive sleep patterns monitoring  and real time data on key sleep metrics such as total sleep time, deep sleep  and sleep efficiency can be achieved using this device. In particular, WHOOP is known for its ability to simultaneously track both levels of activity and recovery, which makes them especially effective for studies that look at how  physical activity and sleep are related to one another. Techwear.com (Miller,  2022) showed that WHOOP could be used to accurately track fluctuations in sleep quality from being exercised, providing insights into the relationship  between physical activity and sleep architecture. This wristband offers an  easy way to watch individual sleep patterns and make more accurate analysis without requiring in depth sleep studies or polysomnography. 

Wearable sleep technology has shown its potential in assessing how sleep changes with  exercise has stimulated studies to understand sleep changes as a function of exercise in  adolescents. Adolescents have a particular vulnerability in sleep disturbances due to rapid  developing bodies, academic pressures, and social demands. Teenagers who face poor sleep  can also face many adverse effects such as poor school performance, behavioural problems,  and future health problems (CDC, 2022). Ensuring that physical activity at school, such as  soccer, affects sleep for adolescents could tell us a lot about how to improve sleep health. 

Participants: 

This study includes a 15-year-old male participant with a consistent routine of physical activity.  The participant plays soccer for 2 hours on Monday, Wednesday, Thursday and usually has  difficulty in falling sleep at night. A WHOOP wrist band is used to track sleep patterns. 

Independent Variable: 

The independent variable is indulging in physical activity (specifically soccer) throughout the first week. I will be playing 2 hours a day on Monday, Wednesday, and Thursday. In the second  week I will not be participating in any physical activity. 

Dependent Variable: 

Total Sleep Time: The time spent asleep by the participant each night, as recorded by the  WHOOP wrist band. 

Deep Sleep Duration: Measured by the WHOOP wrist band, the amount of time the participant  spent in 'deep' (slow wave) sleep, which is considered the most restorative stage of sleep. Sleep Efficiency: Measured as a percentage using the WHOOP wrist band is the ratio of time  the participant spends asleep to time spent in bed. 

Procedure: 

1. Ensure the participant maintains a consistent daily routine, including waking up at 6:30 - 7  AM. 
2. Make sure the participant does not drink any caffeine and make sure they avoid naps to limit  exposure to sleep interference. 
3. Calibrate the WHOOP wrist band and confirm baseline sleep metrics. 4. Make sure that the information in the wrist band tracks total sleep time and deep sleep  duration and sleep efficiency are accurate. 
4. Divide the study period into two separate weeks: With soccer or without. 6. Designate Week 1 as the active week with soccer and make Week 2 a control week in which  the participant does not participate in any physical activity. 
5. For Week 1, have the participant play 2 hours of soccer Monday, Wednesday, and Thursday  from 4 to 6 PM. 
6. Make sure to restrict the participant from further exercise or very physical activity to avoid  inaccurate results. 
7. Using the WHOOP wrist band, record the participant’s bedtime and wake up time each night. 10. Get the total sleep time, deep sleep duration, and sleep efficiency data each night from the  WHOOP wrist band. 
8. In week 2, make sure the participant does not indulge in any physical activity. 12. Throughout Week 2 continue to record bedtime, wake-up time and nightly sleep metrics. 13. Using the WHOOP wrist band, record the participant’s bedtime and wake up time each  night. 
9. Verify WHOOP data works by cross referencing them with manual observations. 15. Calculate weekly averages for all sleep metrics including total sleep time, deep sleep  duration, sleep efficiency, etc. 
10. Compare the average sleep metrics of Week 1 and Week 2 to see how physical activity  affects sleep quality.

Processed Table: 

Interpretation: 

Total Sleep Time: Average total sleep time was 7 hours 14 minutes for the week with soccer versus 5 hours 3 minutes for the week without soccer. This shows that with soccer there is a rise  in sleep duration that is consistent. We can also infer with research that physical activity can  enhance sleep time. 

Deep Sleep Duration: There was notably more of that deep sleep during the soccer week: 2  hours 10 minutes versus 1 hour 45 minutes during the week without any physical activity. These  findings agree with studies that exercise improves slow wave sleep, and overall restorative sleep  (Smith, 2021). 

Sleep Efficiency: Sleep during the week of physical activity had better sleep quality, as the sleep  efficiency was higher (88% vs. 78% without physical activity). Exercise has been shown to  improve sleep quality which has also been linked to increased sleep efficiency (which signifies a  greater portion of restful sleep) (American Academy of Sleep Medicine, 2022). 

Limitations: 

Some limitations should be noted throughout this experiment. While this study offers useful  information in understanding the relation between daytime physical activity and sleep quality,  the experiment might subject to misclassification bias. The first limitation of the study is the  sample size, this experiment was only tested on one participant, which may conclude different  results from other people. The results would have been stronger if the sample was more diverse  and larger. The study was also short, just two weeks, so the experiment may not include long  term effects, or the long-term variation in sleep patterns. 

Another limitation is the control of other possible factors to which can influence sleep metrics  such as daily stress, diet, and environmental changes. The effects of physical activity alone are  hard to isolate from all of these external variables, because they were not measured or  accounted for. Additionally, unlike polysomnography, the WHOOP wrist band is a reliable sleep  tracker, but it may not provide as very accurate results in sleep stage tracking, it may miss many  sleep behaviour nuances. 

Future studies should expand the group to more participants, observe for a longer period of  time and control for other outside factors, such as lifestyle habits and stress. A combination of  wearable devices and clinical methods would also allow for a more comprehensive  understanding of exactly how physical activity impacts sleep. 

Conclusion: 

In conclusion, these results suggest that regular soccer engagement improves sleep quality,  such as sleep duration, deep sleep and sleep efficiency. These results show a contrast between  the week with soccer versus the week without physical activity. In the week with soccer there  was a big jump from the week without soccer (an hour on average of total sleep time over the  week without soccer). According to National Sleep Foundation (National sleep foundation,  2023), this conforms to previous research indicating that exercise can heavily lead to longer  sleep duration by increasing physical fatigue which facilitates easier and more sleep duration  phase leading to more efficient restorative stages. This further matches previous results from  the American Academy of Sleep Medicine (American academy of sleep medicine, 2022),  suggesting that high intensity exercise may increase slow wave sleep, the most restorative part  of sleep. 

Furthermore, while sleep duration and deep sleep were found to be similar with whether soccer was played on the week or not, sleep efficiency was also drastically higher on the week with  soccer by 10%, suggesting that sleep on the week with soccer was, with all things considered,  more restful and undisturbed. What this shows is that physical activity not only optimizes the amount of sleep, but it also improves sleep quality. 

Overall, these results support the hypothesis that daytime physical activity, in particular high  intensity sports such as soccer is associated with better sleep. Regular physical exercise may  also be a beneficial intervention for others, such as students and professionals, who may have  problems with sleep difficulties, because not only can it help to increase sleep duration, but  also to improves sleep quality. The importance of this research is that physical activity can help  sleep which results in better daily performance and wellbeing. However, even though the results  supported the claim that physical activity can help sleep, the results from this study should be  interpreted with caution, given the small sample size and short duration. One of the reasons  being that during the experiment used a consistent routine and did not have control over other  variables (diet and stress for example) leading to the results. These findings need further  validation with a larger sample size and longer observation period, and with control over more  lifestyle factors. 

Reference list: 

American Academy of Sleep Medicine. (2022). Exercise and sleep: Improving sleep with  physical activity. Retrieved from https://aasm.org/ 

Centers for Disease Control and Prevention (CDC). (2022). How much sleep do I need?  Retrieved from https://www.cdc.gov/sleep/index.html 

Miller, J. (2022). Tracking sleep with WHOOP: Insights for athletes. WHOOP. Retrieved from  https://www.whoop.com/thelocker/sleep/ 

National Sleep Foundation. (2023). Physical activity and sleep. Retrieved from  https://www.sleepfoundation.org/physical-activity-and-sleep 

Smith, K. (2021). Aerobic exercise and sleep quality: The benefits of sports for better sleep.  Sleep Health Journal. Retrieved from https://www.sleephealthjournal.org/ 

American Council on Exercise (ACE). (2021). The role of exercise in improving sleep. Retrieved  from https://www.acefitness.org/ 

Johns Hopkins Medicine. (2023). Exercise and sleep: How physical activity affects sleep quality.  Retrieved from https://www.hopkinsmedicine.org/health/wellness-and-prevention/exercise and-sleep 

Sleep Foundation. (2021). The benefits of exercise for sleep. Retrieved from  https://www.sleepfoundation.org/physical-activity-and-sleep 

Mayo Clinic. (2022). Exercise: A healthy habit to help you sleep. Retrieved from  https://www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/sleep/art-20048379 

Harvard Health Publishing. (2021). How physical exercise improves sleep. Retrieved from  https://www.health.harvard.edu/staying-healthy/exercise-to-sleep-better 

World Health Organization (WHO). (2020). Physical activity and young people. Retrieved from  https://www.who.int/