Sleep Characteristics Vary Across Different Countries

Qian Xiao, MPH, PhD

Whether a child lives in a high-income or low-income country could impact the relationship between sleep and health-related quality of life.

A team, led by Qian Xiao, MPH, PhD, University of Iowa, examined whether both device-measured and self-reported sleep characteristics relate to the health-related quality of life of a sample of children from 12 countries.

Previously, investigators have linked short sleep duration, poor sleep quality, and late sleep timing with a lower health-related quality of life in children. Nearly all of these studies relied entirely on self-reported sleep information. These studies were also mostly conducted only in high-income countries.

The current study included a sample of 6626 children between 9-11 years old from a wide range of countries that widely vary in economic terms and human development. The countries included in the study were Australia, Brazil, Canada, China, Columbia, Finland, India, Kenya, Portugal South Africa, the UK, and the US.

Each participant wore a waist actigraphy to measure total sleep time, bedtime, wake-up time, and sleep efficiency on both weekdays and weekends. The children also self-reported ratings of sleep quantity and quality.

The investigators measured the health-related quality of life using the KIDSCREEN-10 survey and used multilevel regression models to determine the relationships between sleep characteristics and the health-related quality of life.

The study results found considerable variation in sleep characteristics, especially for sleep duration and timing, across the 12 study sites. Overall, there was no link between device-measured total sleep time, sleep timing, or sleep efficiency and health-related quality of life.

On the other hand, self-reported rating of poor sleep quantity and quality was linked to health-related quality of life.

“Self-reported, rather than device-based, measures of sleep are related to HRQoL in children,” the authors wrote. “The discrepancy related to sleep assessment methods highlights the importance of considering both device-measured and self-reported measures of sleep in understanding its health effects.”

Recently, investigators found exercise has helps individuals maintain cognitive function during sleep deprivation.

A team, led by Fabien Sauvet, MD, University of Paris, investigated the effects of 7 weeks of moderate and high-intensity interval exercise training on vigilance and sustained attention, inhibition processes and working memory during 40 hours of total sleep deprivation.

Exercise training is known to improve learning and memory and protect against the negative impact of sleep deprivation.

In the study, 16 subjects were evaluated at baseline, during the total sleep deprivation, and the day after a night of recovery sleep. The polysomnographic variables comprised of 6 electroencephalograms, 2 electrocardiograms, 2 electrooculograms, and 2 electromyogram derivations.

Each participants was prohibited from exercise, caffeine, tobacco, alcohol, and other psychoactive substances for the duration of the study, as well as 24 hours prior to beginning the study. Meals and caloric intake were also standardized for all subjects.

The exercise training program included 3 training sessions per week over a seven-week training period on an ergocycle. All 16 participants performed the entire protocol, where maximal oxygen consumption and maximal aerobic power increased after 7 weeks of exercise training (42.8 ± 1.8 vs 47.7 ± 1.7 mL/min/kg, P <0.001; 236 ± 43 vs 266 ± 38 W, P <0.001).

The investigators found the exercise training effects during the night recovery resulted in lower stage-3 sleep and higher rapid eye movement sleep duration. This effect was also discovered on free insulin-like growth factor I levels with lower levels during total sleep deprivation at post-exercise training.

The study, “Sleep characteristics and health-related quality of life in 9- to 11-year-old children from 12 countries,” was published online in the Journal of the National Sleep Foundation.