A massive global study has turned up some grim news: that nearly 87% of us are not routinely getting quality sleep and meeting physical activity levels needed for our long-term health. Now, scientists have discovered that one is more influential than the other.
In an effort to understand more about the biodirectional relationship between sleep and exercise, Flinders University researchers pooled worldwide health data from 70,963 users of two consumer-available health devices – an under-mattress sleep sensor and wrist-worn health tracker – between January 2020 and September 2023. Rather than gather a snapshot, the roughly 3.5 years allowed scientists to spot patterns as well as day-to-day information.
What they found was that, overall, just 12.9% of the cohort routinely achieved both quality sleep of seven-to-nine hours and the recommended daily 8,000 steps or more. What’s more, almost 17% of participants routinely got both less than seven hours of sleep a night and managed fewer than 5,000 steps a day.
But perhaps the most interesting aspect – since being time-poor and underslept probably won’t come as a shock to anyone, especially at this time of year – was just how the two activities interact with each other. The 12.9% who were both good sleepers and movers showed a marked improvement in physical activity the day following quality shut-eye. Essentially, their daily movement dropped off after nights where they achieved fewer hours asleep – even though, on average over the 3.5 years, they still fit into the “seven-to-nine hours a night” bracket.
The findings suggest that when it comes to setting sleep and physical activity recommendations, they should be considered as two sides of the same coin rather than independent of each other. And, to date, there’s a lot more data on the type of exercise to do, in order to sleep better. The researchers argue that more of an emphasis needs to be put on prioritizing sleep to set a good foundation for then being more active the next day.
“We found that getting a good night’s sleep – especially high-quality sleep – sets you up for a more active day,” said lead author Josh Fitton, a PhD candidate at Flinders University. “People who slept well tended to move more the following day, but doing extra steps didn’t really improve sleep that night. This highlights the importance of sleep if we want to boost physical activity.”
And, according to the data, more sleep didn’t mean increased physical activity – there was a threshold where anything beyond seven hours seemed to have little impact on movement.
“Our data showed that sleeping around six to seven hours per night was linked to the highest step counts the next day,” said Fitton. “But that doesn’t mean you should cut back on sleep because quality is just as important. People who slept more efficiently, meaning they spent less time tossing and turning, were consistently more active.”
The study also highlights how, for the majority of people, it’s a challenge to lock in both enough sleep and steps for our wellbeing – something that 87.1% were unable to achieve on average.
“Our findings call into question the real-world compatibility of prominent health recommendations and highlight how difficult it is for most people to have an active lifestyle and sleep well at the same time,” Fitton added. “Only a tiny fraction of people can achieve both recommended sleep and activity levels every day so we really need to think about how these guidelines work together and what we can do to support people to meet them in ways that fit real life.”
While getting better-quality shut-eye is often easier said than done, the researchers suggest that we need to reframe the act of sleep as just those hours between living our lives and appreciate its important role in our health.
“Prioritizing sleep could be the most effective way to boost your energy, motivation and capacity for movement,” said senior author Danny Eckert, a professor at Flinders University. “Simple changes like reducing screen time before bed, keeping a consistent bedtime, and creating a calm sleep environment can make a big difference.
“Our research shows that sleep is not just a passive state, it’s an active contributor to your ability to live a healthy, active life.” he added.
Supporting this research is another new study from scientists at the University of Michigan, who found that dopamine neurons are particularly active during nonrapid eye movement (NREM) sleep – which supports our reward and motivation brain signals when we’re awake.
They found that this dopamine spike is synchronized with memory-boosting sleep spindles, helping to strengthen motor memories and improve motor skills. This challenges traditional thought that these dopamine neurons only serve this role when we’re fully conscious.
“As alterations in dopamine signaling are associated with neurodegenerative diseases that also involve motor deficits and sleep disturbances, understanding these links could pave the way for improved therapeutics and advancements in human health,” said the Science Advances study co-author Ada Eban-Rothschild, an associate professor at the University of Michigan. “The findings highlight that sleep is an active biological period during which key neural circuits strengthen the skills and patterns we rely on every day.”
The research was published in the journal Communications Medicine.
Source: Flinders University
