Relationship between Exercise and Sleep Based on the Latest Data
The relationship between exercise and sleep has been widely studied for many years. It has been reported that appropriate exercise can alleviate sleep-related problems and allow for sufficient rest. Recent research also suggests that insufficient or poor quality sleep can lead to decreased physical activity the following day.
For these reasons, experts today believe that sleep and exercise have a bidirectional relationship. This means that improving exercise habits can lead to better sleep, and getting enough sleep can make daily exercise more efficient.
How does exercise affect sleep?
Regular exercise offers various benefits, including reducing the risk of diseases like cancer and diabetes, and improving physical function and quality of life. Exercise is also beneficial for specific groups; pregnant women who exercise regularly are less likely to gain excessive weight or experience postpartum depression, and elderly individuals who exercise are at lower risk of falls and injuries.
Exercise improves sleep quality for many people. Specifically, moderate to vigorous exercise in adults shortens sleep onset latency (the time it takes to fall asleep) and enhances sleep quality. Furthermore, exercise has also been found to reduce daytime sleepiness and can decrease reliance on sleeping pills for those who struggle to fall asleep without them. Exercise also indirectly improves sleep; moderate exercise reduces the risk of excessive weight gain, making symptoms of obstructive sleep apnea (OSA) less likely. Approximately 60% of moderate to severe OSA cases are attributed to obesity.
Numerous surveys have been conducted on sleep and exercise habits in adults. One such survey is the "Sleep in America" study conducted by the National Sleep Foundation in 2003, targeting adults aged 55 to 84. Approximately 52% of the respondents in this survey reported exercising three or more times a week, while about 24% exercised once a week or less. The latter group of respondents tended to report less than six hours of sleep per night, poor or fairly poor sleep quality, difficulty falling asleep or maintaining sleep, and diagnoses of sleep disorders such as insomnia, OSA, or restless legs syndrome.
The 2013 "Sleep in America" public opinion poll, which focused on "exercise and sleep" among adults aged 23 to 60, yielded similar results. Approximately 76-83% of respondents who engaged in light, moderate, or vigorous exercise reported having very good or fairly good sleep quality. This figure dropped to 56% for those who did not exercise.
Similar studies and surveys have also looked at the effects of exercise on subjects in other age groups. One study on university students during exam periods found that exercise and active physical activity reduced exam-related stress. Another study noted that sleep and exercise in older adults are "closely intertwined." Furthermore, it was found that regular aerobic exercise in OSA patients reduced symptoms, even without weight loss.
Compared to exercise, considering the workload of manual laborers as physical activity, it is often not enough to resolve sleep problems. One reason for this is that much physical labor can cause musculoskeletal pain and discomfort, which can negatively impact sleep.
Is exercising before bed harmful?
Whether exercising in the hours leading up to bedtime degrades sleep quality has been a hotly debated topic for many years. Conventional sleep hygiene suggests that intense exercise within three hours of bedtime can negatively affect sleep by increasing heart rate, body temperature, and adrenaline levels. Conversely, some research indicates that exercise before bed does not have an adverse effect.
One survey found that the majority of people who exercised after 8 PM fell asleep faster, experienced deeper sleep, and woke up feeling well-rested. Respondents who exercised between 4 PM and 8 PM showed similar percentages in these areas, suggesting that late-night exercise can actually be beneficial for some individuals.
Other studies have yielded similar results. One study reported that subjects who exercised at night had more slow-wave sleep, longer rapid eye movement sleep, and less light sleep compared to the control group. However, it also noted that the increase in body temperature that occurs after intense exercise is associated with reduced sleep efficiency and increased wakefulness after sleep onset. Thus, while pre-sleep exercise is not universally harmful, intense exercise within one hour of bedtime may affect sleep efficiency and total sleep time.
Nevertheless, survey results indicate that an overwhelming majority of people do not exercise within one hour of bedtime. The aforementioned "Sleep in America" survey conducted in 2005, which targeted adults aged 18 and over, found that 4% of respondents exercised within one hour of bedtime every night, 7% exercised a few nights a week, and 5% exercised a few nights a month before bed. The remaining respondents rarely or never exercised within one hour of bedtime, or declined to answer.
When exercising before bed, it is advisable to choose the timing and intensity that suits your own sleep style. Practices such as yoga, light stretching, and breathing exercises are particularly said to promote good sleep.
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How does sleep affect exercise?
The role of sleep on the body has not been extensively researched, and many studies have focused on differences in physical activity between individuals with sleep disorders and those with healthy sleep.
Many of these studies conclude that sleep-deprived individuals exercise less than those with healthy sleep cycles, and it is particularly said that individuals with certain sleep disorders tend to have lower levels of physical activity during the day. Adults with insomnia tend to be less active than those without it, and the same applies to those with sleep-disordered breathing like OSA, although being overweight may also be a contributing factor to sleep deprivation in such groups.
Several studies indicate that changes in the quality, depth, and efficiency of nightly sleep can predict levels of physical activity.
While many studies to date have shown a relationship between high-quality sleep and healthy levels of physical activity, it has not been clearly proven that high-quality sleep directly leads to increased physical activity levels.
One study reported that continuous positive airway pressure (CPAP) therapy, a first-line treatment for OSA, applied for 1 to 6 months, alleviated OSA symptoms and improved sleep, but had no significant effect on physical activity levels. Furthermore, when CPAP therapy was combined with dietary improvements, dietary changes were successful, but there was little meaningful adjustment in exercise volume.
The key takeaway here is that while getting good quality sleep can provide sufficient rest and boost motivation for exercise the next day, healthy sleep alone may not spontaneously change how or how often one exercises.
How was it?
Sleep and exercise influence each other; improving exercise habits can lead to better sleep quality, and getting enough sleep can help you make more effective use of your daily exercise. If you recognize any of these points in your daily life, please consider incorporating moderate exercise into your routine.
