Study details and key findings

For the study, researchers analyzed data from almost 60,000 participants in the UK Biobank, a longitudinal health study. The participants were followed for an average of eight years and provided information about their diet. The researchers scored each participant's diet on a scale of 0 to 100, with a higher score indicating a healthier diet. A subset of the participants also wore wrist watches to track their movement and sleep.

Using this data, the researchers created a statistical mortality model to predict longevity and health span, which was defined as the number of years free of cardiovascular disease, dementia, chronic obstructive pulmonary disease, and type 2 diabetes.

Participants with the poorest sleep, physical activity, and nutrition (SPAN) habits were used as a reference point. These participants slept 5.5 hours a night, exercised for 7.3 minutes a day, and had a diet quality score of 36.9.

According to the researchers, the ideal mix of SPAN habits was at least 7.2 hours of sleep, 42 minutes of physical activity a day, and a diet quality score of at least 58. This combination of habits was associated with a 9.35-year increase in longevity and 9.46-year increase in health span compared to participants with the lowest SPAN numbers. 

Improvements in just a single behavior could also help improve participants' health and longevity. An extra 25 minutes of sleep per night, an extra 2.3 minutes of exercise per day, or a 35.5 increase in diet quality score could also increase participants' lifespan by one year.

"All those tiny behaviors we change can actually have a very meaningful impact, and they add up over time to make a big difference in our longevity," said Nicholas Koemel, research fellow in the University of Sydney's department of physical activity, lifestyle and population health and the study's lead author.

However, the researchers also highlighted limitations to the study, including the fact that it used self-reported dietary information and only had relatively brief recordings of sleep and exercise. Since it was a modeling study, it was built on predictions rather than real people.

"All of the gains reported in this study are theoretical," Koemel said. "We cannot claim a direct causal effect from the lifestyle patterns. These findings should therefore be interpreted as expected or projected benefits under assumed behavioral variations, rather than confirmed effects of an intervention."

Overall, "[t]he message here should not necessarily be that making these small tweaks is a silver bullet," Koemel said. "It's more so about where we take that first step and trying to look at how we can make sustainable opportunities that are more achievable for some people."