Exercise and Sleep: Snoozing Till The Sun Comes Up

Sleeping disorders are increasingly common in modern societies, with 10-50% of the adult population being affected globally.

Sleep loss and disturbances negatively influence well-being and health, potentially causing daytime sleepiness as well as affecting moods and mental abilities. Long-term sleeping problems are also associated with illnesses such as cardiovascular diseases, obesity and depression. 

Individuals with high levels of fitness tend to report better quality of sleep and have less problems falling asleep. Regular aerobic exercises and stretching are simple and effective strategies to get a good night’s sleep, although it is important to exercise at the correct intensity and time of day. 

Why is sleep important?

Sleep occupies approximately one-third of your life and thus plays a correspondingly important role in maintaining health and function. During sleep, your body recovers energy from the day’s activities and allows the mind to consolidate important memories.

Inadequate or disturbed sleep will not only result in increased fatigue and sleepiness during the day, but also make you more irritable and prone to depression, diminished memory and learning abilities. Moreover, when you are tired and sleepy from a poor night’s sleep, you are more likely to make mistakes at work during the day, which could increase the risk of hurting yourself accidentally.

Prolonged periods of poor sleep patterns can also affect your immune system and have been associated with illnesses such as cardiovascular diseases, type 2 diabetes, obesity, anxiety disorders and depression. Besides having a regular diet and exercise, getting good quality sleep is just as important for maintaining good health.

Who are affected by sleeping disorders?

Although there are no official figures, it is estimated that there may be around 800,000 Singaporeans suffering from sleeping disorders, with women and older adults being more at risk. This figure has increased steadily over the years and is comparable to other countries. As Singapore’s population continues to age, the proportion of people affected by sleeping disorders will likely grow.

What can you do to improve sleep quality?

Although drugs and medication can help improve the quality of sleep, long-term use can lead to drug dependence and drug tolerance may require higher doses to be effective.

People who exercise regularly and are physically fit fall asleep faster, experience sounder sleep and feel more refreshed upon waking up. They also experience less daytime sleepiness, depression and enjoy improved quality of life. Simple and inexpensive, exercise can help people who struggle with sleeping disorders.

There are three reasons why exercise may help improve your sleep quality. Exercise can stabilise the body’s internal clock and reduce daytime sleepiness, thus helping the body maintain uninterrupted sleep at night.

Studies have shown that highintensity exercises increase the amount of the sleep-promoting substance, adenosine, in the body. Lastly, exercise also helps to ease anxiety and stress – important factors that may disturb sleep.

Types of exercises that can help improve sleep quality

When done at moderate intensity (60-75% of maximum heart rate*), aerobic exercises such as jogging, stationary cycling or treadmill walking have been found to be beneficial for improving sleep quality.

The exercises should be done for 35-45 minutes per session, at least four times a week. You may need about four to six weeks to get used to the exercise, so it is advisable to start at 15-20 minutes for the first two weeks, at 55-65% of your maximum heart rate and slowly build up your endurance to the recommended intensity.

The timing of the exercise also plays a role in affecting sleep quality. Studies found that morning exercisers who did aerobic exercises for at least 225 minutes (five 45-minute sessions) a week had less trouble falling asleep, as compared to others who exercised for less than 180 minutes (four 45-minute sessions) a week. However, this trend of improving sleep quality through increasing amounts of exercise was not noted in people who exercised in the evening or at night.

Exercising in the evening or at night before sleep is not an uncommon practice as most people believe physical fatigue is equivalent to sleepiness. Although this may not be entirely correct (you can feel tired, but not sleepy after a vigorous sprint), there may be a reason why some people report sleeping better and feeling more refreshed after exercising late at night.

During deep sleep, the body’s core temperature will decrease rapidly. This phenomenon may be mimicked when the heated body cools down after exercising, tricking the body to slip into sleep easily.

Although late-night exercise does not seem to affect the quality of sleep significantly, the body’s heart rate can remain elevated during sleep for up to three hours. This reduces time for the heart rate and blood pressure to decrease. However, it is important to note that chronically elevated blood pressure may produce wear and tear on the cardiovascular system.

Rather than exercising vigorously at night, studies have found that 15-30 minutes of low-intensity stretching of the upper and lower body can also improve sleep quality. Stretching helps reduce muscle stiffness and helps the body to relax and prepare for sleep.

Conclusion

Sleeping disorders can be frustrating, but when done correctly, regular aerobic and stretching exercises are simple yet powerful remedies to help manage them.

References 

  • Reid KJ et al (2010). Aerobic exercise improves selfreported sleep and quality of life in older adults with insomnia. Sleep Medicine. 11(9): 934-940. 
  • Myllymaki T et al (2011). Effects of vigorous late-night exercise on sleep quality and cardiac autonomic activity. Journal of Sleep Research. 20: 146-153. 
  • Tworoger SS et al (2003). Effects of a year-long moderate intensity exercise and stretching intervention on sleep quality in postmenopausal women. SLEEP. 26(7): 830-836. 
  • Youngstedt SD and Kline CE (2006). Epidemiology of exercise and sleep. Sleep and Biological Rhythms. 4: 215-221. 

 

Mr Chen Yanzhang
Mr Chen Yanzhang is a Physiotherapist at the Musculoskeletal Outpatient Department at Tan Tock Seng Hospital. He graduated from Curtin University with a Bachelor of Science (Physiotherapy) in 2009. He has a special interest in exercise and strength training for the elderly.