They claim that people born at certain times of the year have a far greater chance of developing certain types of temperaments, which can lead to mood disorders.

The scientists, from Budapest, said this was because the seasons had an influence on certain monoamine neurotransmitters, such as dopamine and serotonin, which control mood, however more research was needed to find out why.

They discovered that the number of people with a “cyclothymic” temperament, characterised by rapid, frequent swings between sad and cheerful moods, was significantly higher in those born in the summer.