Mental Viagra’ is on the horizon after scientists discovered that a hormone which surges during puberty can activate lust signals in the brain.

The hormone kisspeptin essentially switches on the desire to reproduce and is linked to feeling sexy, romantic and turned on. It is thought to be responsible for the voracious sexual appetite of young people.

Now scientists at Imperial College London have found that an injection of kisspeptin can trigger chemicals in the brain which occur when people feel amorous and aroused.

They believe that pills containing the hormone could one day be used to treat sexual problems which are psychological – rather than physical.

It could even help couples recapture the spark in a failing relationship.