Key Points

The study, led by researchers from Flinders University in South Australia, is based on data from more than 116,000 adults and over 73 million nights of sleep. The team used an under-mattress device to objectively track sleep duration and timing across 3.5 years, Xinhua news agency reported.

The study finds that sleep is shaped not just by personal habits, but by environmental factors like daylight, temperature, and weekly routines.

"Our findings underscore the seasonal nature of human sleep, and that it is influenced by demographics and geography," said Hannah Scott, a sleep health expert at Flinders University.

People in the Northern Hemisphere sleep 15 to 20 minutes longer in winter, while those in the Southern Hemisphere sleep less in summer.

"Interestingly we found that the farther you live from the equator, the greater the seasonal variation in sleep," Scott said.

People go to bed later and sleep in longer on weekends, recovering some lost sleep, especially middle-aged adults balancing work and family.

These irregular patterns are increasingly linked to negative health effects, according to the study published in Sleep.

The study found a gradual decline in sleep, with people sleeping about 2.5 minutes less per night from 2020 to 2023, possibly due to the ongoing effects of the Covid-19 pandemic.

"Irregular sleep is more than just feeling tired -- it can be a health risk and understanding how our routines and environments affect sleep is a helpful step towards improving it," said Danny Eckert from Flinders University.

Although the study focused on tech-savvy users and didn't account for factors like pets or partners, it underscores how the environment shapes sleep, reminding people to consider time and season for better rest, said the researchers.

- IANS