Scientists have said that lots of sunshine increases the level of the male sex hormone testosterone.
Ninety per cent of the body's vitamin D is produced by the action of sunlight on the skin.
And the researchers at the Medical University of Graz, Austria, said sufficiently high levels of the vitamin have a "positive influence" on testosterone, the Daily Express reported.
They found that men with high blood vitamin D levels have significantly higher testosterone levels than men with less vitamin D.
"Men who ensure that their body is at least sufficiently supplied with vitamin D are doing good for their testosterone levels and their libido," said Ad Brand, of the Sunlight Research Forum, in Holland.