The index, developed by researchers Oxford Economics, found that quadrupling your income causes very little increase to your happiness, while spending time in the bedroom is a lot more significant.
Polling carried out by the National Centre for Social Research, found that the most rested people score 15 points higher on the index than those who struggled with their sleep.
People who are deeply dissatisfied with their sex lives score seven points lower on average than those who say they were very satisfied.
By the same metric, increasing household income from £12,500 to £50,000 results in an increase of just two points.
The study, commissioned by Sainsbury’s, will return to the same respondents every six months to see how changes in their lives affect their happiness.
“For the typical Brit, improving their sleep to the level of someone at the top of the Index would be equivalent to them having over four times as much disposable income,” the report said, adding that sleep was the “strongest indicator of a broader sense of well-being”.
Other factors including living in a strong community, job security and the health of close relatives were also more significant than income.
Ian Mulheirn, director of consulting at Oxford Economics, said: “The richness of our relationships and support networks remains among the biggest determinants of how well we live – and represents an area of our lives in which we can act.”
The analysis also found that young families were the happiest demographic group overall. There was a strong association between happiness and having a young child at home.
“Baby boomers” who were still in work were the second-happiest group because of good job security and a high standard of living.
Child-free people in their 30s and 40s were the least happy because they have “weaker support networks” and lower levels of satisfaction with their sex lives, it said.
The average person scored 62.2 out of 100 on the scale. Those at the top of the scale – scoring between 72 and 92 – were more likely to be satisfied with their sex lives and sleep than the average person.The survey of 8,250 adults also found that older people are objectively happier than younger ones – even when other factors, such as wealth and lifestyle, are controlled.
For all levels of disposable income, a 50 per cent rise contributes to just a 0.5 point increase in their score.
People who spent less time outdoors, had been in debt, drank heavily and socialized less often were also likely to be more unhappy.
Being married, living in the countryside and talking to neighbors were other factors associated with happiness.
“The typical person speaks to their neighbors once or twice a month. But doing so as much as people in the top 20 per cent of the Living Well Index – among whom almost 70 per cent speak to neighbors once or twice a week – could add 1.6 points to their index scores,” the report added.
The analysis also found that whether someone rented or owned their own home was irrelevant to well-being, and heavy social media usage was also not a factor which was linked to increased unhappiness.