Australians have the earliest bedtime of any country, according to a new study of global sleep patterns. The University of Michigan research also found that Spaniards were the latest to bed, the Dutch got the most sleep, and people in Singapore and Japan were the most sleep-deprived. The study used a free smartphone app aimed at reducing jetlag to collect sleep data from more than 5400 people in 100 countries. It found that social and cultural pressures can override natural circadian rhythms, particularly at bedtime, leading to delayed bedtimes. But those who went to bed later didn't necessarily sleep later, meaning they tended to lose out on sleep. "Across the board, it appears that society governs bedtime and one's internal clock governs wake time, and a later bedtime is linked to a loss of sleep," said Daniel Forger, professor of mathematics at the University of Michigan and co-author of the study published by the American Association for the Advancement of Science in the journal Science Advances. The study found Australians were the first to turn in, heading to bed just after 10.45pm - about an hour earlier than the Spanish, who had the latest bedtime.