Her tearful tantrums and dramatic outbursts on Love Island alarmed viewers and even prompted her doctor to intervene with the ITV1 reality show's producers.

But model Sophie Anderton - who has beaten drug addiction and alcoholism - has a genuine reason for her erratic behaviour and mood swings.

For she has been diagnosed with bipolar disorder, which triggers periods of mania followed by depression.

"Sophie has recently been told she has the condition," says my source who got close to the former Gossard supermodel on the show. "She has to take mood stabilisers, which are helping to control her temperament and keep her more balanced."

Comedian Stephen Fry was diagnosed with bipolar - which used to be called manic depression - when he was 37 and said at the time: "It explains the massive highs and miserable lows I've lived with all my life."

The diagnosis will go some way towards explaining 29-year-old Sophie's erratic and colourful love life. She has repeatedly expressed a desire to settle down with the right man, yet has dated a selection of exciting, yet unsuitable, playboys, nightclub owners and footballers.

More often than not the relationships ended in tears and on one occasion, after a violent argument with disgraced former Chelsea goalkeeper Mark Bosnich, in hospital with severe bruises.

Now Sophie, right, is busy making plans to move on and live with bipolar. After spending the summer in the sunny climes of Fiji she plans to spend next spring trekking across the Arctic Circle in Canada to raise money for a children's charity.

She will be accompanied by Nick Gold, son of legendary restaurant entrepreneur Johnny Gold, and seven other hardy souls.

"The plan is to cover 144 miles across Baffin Island in about two weeks," Nick told me at the launch of Frankie's Bar and Grill at Selfridges last week.

"The temperatures will be around -30C, so at night we're going to pitch up our tents on the ice and hope we wake up in the morning."