Date nights, sleeping naked , holding hands and kissing more often can help to keep your love life alive, according to a survey of over 100 000 respondents from around the world.

We're used to studies espousing data on how the "average" person behaves, but never before has such information been linked to how happy or unhappy such behaviour makes them.  

That is until now. Chrisanna Northrup, described as a "wellness entrepreneur", had the idea to investigate the tried and tested behaviour that couples who are happy engage in.

Pepper Schwartz and James Witte - both sociologists - helped Northrup conduct and analyse an online survey to find out these secrets of successful relationships. By analysing age and gender, racial and geographic differences and sexual preferences of the respondents, they discovered some interesting results.

It seems one such "secret" to improved sexual satisfaction is to sleep naked, while kissing outside of having sex is another important action. In fact, the data suggests that those who kiss affectionately are more sexually satisfied than those who only kiss during sex.

Schwartz says that even couples professing to be happiest have some things they'd secretly like to adjust.

"If you look at the happiest couples, they do have date nights. They hold hands. They do PDAs [public displays of affection]. That whole package of romance that some couples preserve - that shows how important it is," she told the Daily Mail.

Overall, it seems communication is among the top secrets to a healthy and happy relationship, while friendship, affection and sex follow close behind.   

Northrup and her colleagues have written a book based on analysis of the survey entitled The Normal Bar, describing it as both portrait of how real couples behave as well as a roadmap for anyone looking to find a deeper level of satisfaction in their relationship.