Smartwatch Data Identifies Various Cultures' Sleep Patterns

Scientists have studied the quality and hours of sleep from different cultures and individual backgrounds using Nokia smartwatches.

The research, published in the Scientific Reports by researchers from the Korea Advanced Institute of Science and Technology (KAIST) and Nokia Bell Labs in the United Kingdom, conducted the study to understand the cultural and personal aspects that affect sleep.

The scientists employed commercially available smartwatches for extensive data collection, evaluating 52 million logs gathered over four years from 30,082 individuals in 11 countries, in contrast to other studies that focused on surveys or lab-based controlled trials. Based on the digital logs from the devices, the team's use of the Nokia smartwatches allowed them to look at regional variations in sleep habits.

Digital logs taken from the smartwatches showed differences in wake-up and sleep periods from the information previously gathered via self-report evaluations, often by tens of minutes to an hour. The average wake-up time was 7:42 AM, while the average sleep duration was estimated to be approximately midnight overall.

However, the researchers found that their geographic location and cultural characteristics strongly influence people's sleep. Wake-up timings were comparable, while sleep schedules differed per nation. People in countries with greater GDPs reported staying up later. Individuals in individualist culture had fewer records of delayed bedtime, whereas those in collectivist society had more.

Japan had the shortest average total sleep time among the surveyed nations, clocking in at around 7 hours, while Finland had the longest, averaging 8 hours.

Researchers assessed important sleep metrics used in clinical investigations, such as sleep efficiency, duration, and overslept weekend hours, to evaluate complicated sleep patterns.

According to a cross-country analysis, societal variables are responsible for 63% of the variance in sleep quantity and 55% of the variation in sleep quality. Because going to bed early is more common in civilizations with higher individualism indices (IDV), which place more value on individual accomplishments and relationships, these societies also had much longer sleep lengths.

On the other side, while having the most significant collectivist values (low IDV), Spain and Japan had the later bedtimes planned. The study also found a weak correlation between improved sleep quality and a higher uncertainty avoidance index (UAI), which gauges how generally applicable laws and regulations are in people's day-to-day activities.

Researchers also examined the relationship between physical activity, sleep duration, and quality to determine whether people may counteract cultural impacts through individual interventions.

They found that increased daily exercise can enhance sleep quality by reducing the time needed to fall asleep and wake up. However, people who exercised more did not get more sleep. The impact of exercise varied by nation, with some seeing more dramatic implications than others, including the United States and Finland.

Notably, exercise didn't have any noticeable effects in Japan. These results imply that there may be cultural differences in the link between daily activity and sleep, as well as possible cultural differences in the effectiveness of various exercise regimens.

According to the study's lead author, Shaun Sungkyu Park, while it is interesting to see how society can influence how much and how well a person sleeps using extensive data, the study's significance lies in the fact that it quantitatively demonstrates how individual actions like daily exercise can improve sleep quantity and quality even within the same culture.

Sleep not only has a great impact on one's well-being but it is also known to be associated with health issues such as obesity and dementia. In order to ensure adequate sleep and improve sleep quality in an aging society, not only individual efforts but also a social support must be provided to work together.

- Lead author Meeyoung Cha

By making a code that quickly calculates the sleep indicators created in this study accessible for free and offering the benchmark data for different types of sleep research to follow, the research team will help the growth of the high-tech sleep sector.