Your optimal amount of sleep may depend on where you live, new University of British Columbia research has found. An analysis of sleep data and health outcomes for nearly 5,000 people in 20 countries revealed that the hours of sleep required for good health vary significantly across different cultures, challenging the common belief that everyone needs the same amount.

"Despite the common advice to get eight hours of sleep, our findings suggest that sleep recommendations need to be adjusted based on cultural norms," said Dr. Steven Heine, professor of social and cultural psychology at UBC and senior author of the study published in Proceedings of the National Academy of Sciences. "There is no one-size-fits-all amount of sleep that works for everyone."

The study confirmed previous findings that average sleep time can vary widely from country to country. For example, the average in Japan was six hours and 18 minutes, while in France it was seven hours and 52 minutes. In Canada, it was seven hours and 27 minutes.

Other studies have found links between shorter sleep durations and poor health outcomes. However, this collaboration between UBC and University of Victoria researchers was the first to investigate whether people from countries with shorter sleep durations suffer from worse health.

The researchers found no evidence that people in countries with less sleep were less healthy than those in longer-sleeping nations.

"People who slept closer to their own culture's norms for sleep duration tended to have better overall health," said Dr. Christine Ou, assistant professor in the school of nursing at UVic and the study's lead author.

"This suggests that the ideal amount of sleep is the amount that matches what is considered appropriate sleep in one's cultural context."

The researchers also discovered that in all 20 countries, people appeared to be sleeping at least one hour less than what was considered optimal for their culture.

The research underscores the importance of considering cultural context when making recommendations about sleep. It suggests that public health guidelines should be tailored to fit the cultural norms of different populations to promote better health outcomes.

Data for the study came from people in North America, Europe, Asia, Africa and South America.