New research suggests spending money really can make us happier, as long as we're spending it on making more free time for ourselves – by employing a cleaner or paying to get the car washed, for instance.

An international team of researchers surveyed 6,271 people across the US, Canada, Denmark and the Netherlands, and found the same link between buying time and life satisfaction irrespective of the overall level of income.

Study participants were asked whether they spent money to buy themselves free time, and if so how much they spent each month. They were also quizzed on how satisfied they were with their lives and how pressed for time they felt.

Across the board, those who spent money to free up time reported greater life satisfaction overall, the researchers report, leading to less time pressure and a better mood.

"The benefits of buying time aren't just for wealthy people," says one of the team, Elizabeth Dunn from the University of British Columbia in Canada." To our surprise, we found the same effects across the income spectrum."

We've also seen studies that suggest the happiness we get from spending money depends on our personalities – so there's unlikely to be a one-size-fits-all solution.

This new research also discovered that very few of us make time-saving purchases in our day-to-day lives. Within the sample, 818 millionaires were asked about their spending habits, and almost half of them weren't spending any money on outsourcing time-consuming tasks.

In other words even though delegating tasks and making more time for ourselves is good for our sense of contentment, it's not something we seem all that keen to do.

One reason could be that paying for a cleaner or to get the shopping delivered makes us feel like we don't have control over our own time, suggest the researchers.

"My take home message is, 'think about it, is there something you hate doing that fills you with dread and could you pay somebody else to do that for you?'," Dunn told Helen Briggs.

"If so, then science says that's a pretty good use of money."