It's known as the "Goldilocks day": the "just right" way to allocate your time to various activities for optimal health.
Sounds like a handy guide to life, right? But is it even possible?
We already have guidelines around how much physical activity adults should get each week. So how many hours each day should we spend standing, sitting or sleeping?
New Australian research published in Diabetologica provides an hour-by-hour breakdown of daily activities to reduce the risk of cardiometabolic diseases, which include disorders of the heart, diabetes and chronic kidney disease.
The study, from Swinburne University and the Baker Heart and Diabetes Institute, analysed more than 2,000 people in the Netherlands, 684 of whom had type 2 diabetes.
Over seven days, they had their waist circumference, blood glucose and insulin levels, cholesterol, blood pressure and triglycerides (a type of fat found in blood) measured.
By examining how participants with the healthiest results divvied up their time, the researchers came up with what they say is an optimum day for cardiometabolic health.
"I think people might kind of baulk at the idea of these strong quantitative guidelines, but the take home message here is we really want people to sit less, move more and sleep for appropriate durations," Dr Brakenridge says.
The average Australian sits for about eight hours a day but desk-based office workers can spend around 10 hours seated.
And most of us only get two hours of physical activity each day (that's light and moderate activity combined), which is about half of what the study recommends.
Light physical activity includes slow walking or doing chores, and moderate to vigorous activity can be brisk walking, jogging or difficult tasks like shovelling.
Doing chores like ironing counts towards your light physical activity. (Getty Images: Eva-Katalin)
Dot Dumuid is a time-use epidemiologist at the University of South Australia. For years she's studied the healthiest ways to spend our time.
She provided statistics for the new study, and noted its narrow focus on cardiometabolic risk factors.
"I like when studies put other outcomes in there as well, like cognition, for example."
Dr Dumuid says very few study participants managed four hours of activity day in, day out.
"There'd be a few super-achievers … but that's not feasible for heaps of people.
"You could do it, but you'd have to give up something else."
And that activity trade-off is where things get interesting.
Adjusting the levers of your life
The perfect day for your heart might be quite different to the perfect day for your brain.
Dr Dumuid has studied the "optimum" 24 hours for a range of health outcomes, and is particularly interested in what happens when you take time from one category and put it in another.
For example, physical activity is great for heart health. But if it comes at the cost of sleep, Dr Dumuid says that can be detrimental for those with anxiety and depression.
And people need to spend more hours sitting than moving if they want to optimise academic performance and cognitive function, as that's when we usually do things like study, read or play music.
While Dr Dumuid is yet to come up with a "Goldilocks day" for adults, she has one that she says is most beneficial for the mental, physical and cognitive function of children aged 11 and 12.
But even with children, priorities can shift, and if exams are approaching, a student might need to temporarily adjust the dial to manage their time differently.
To help with this, Dr Dumuid developed an online tool which lets students rank what's most important to them to give a more personalised 24-hour breakdown.
"One size rarely fits all in population health," she says.
More than one optimum day
No matter how much time we want to invest in being happy and healthy, not everyone has complete agency over how they spend their day.
There can be many limitations depending on where you live, what you earn and whether your capacity is restricted, for example, by chronic health conditions.
And the daily activity combinations researchers looked at in the new study didn't incorporate things like social interactions, which can improve mental and physical health.
So how many hours a day should we spend socialising? Recent research in Nature found there's no universal balance between solitude and socialising.
In fact, solitude (when the person chooses it) can reduce stress levels.
This is another reason why Dr Dumuid thinks we'll never have one single optimum day for overall health.
Instead, perhaps we'll one day have multiple "best days" with different purposes.
"In the future you might wake up and decide 'OK, today I want to preference my mental health, let me see what my options are.'
"Then you focus on something else the next day, and then over a week you can balance it out to be a good, healthy week."
Dr Brakenridge hopes his findings will be used by the federal government to update current health guidelines so they can better reflect the full spectrum of human behaviour.
He says Australia should look to Canada, which has the world's first 24-hour movement guidelines that lay out how much time adults should spend doing aerobic activities, muscle strengthening, sleeping, sitting and using a screen.
By health reporter Paige Cockburn
