Thinking of a treasured memory or listening to a song that evokes a particular time and place in your life doesn't just make you feel good, it can be motivational too. Research shows that reflecting on life experiences that make you nostalgic can lead to increased happiness.

When Coca-Cola brought back '90s favourite Surge, it sold out online within hours. And it's not the only 'revival brand' that's been brought back due to nostalgic consumer demand. But what makes a brand re-issue a discontinued product? And what's driving Gen Y's nostalgia trip?

Three years after Hostess – the manufacturer of sugar-filled goodies such as CupCakes, Ding Dongs, Ho-Hos and Twinkies – went into liquidation for the final time, the company is back, and stronger than ever. As people view sugar with increasing disdain, how has Hostess gotten back on the horse?

From bubblegum-flavoured jelly beans to Haribo cola bottles, there are some tastes that will always remind people of their childhood, taking them right back to the good old days. 'Birthday cake' is emerging as another nostalgic flavour and sweet brands are reintroducing it.