  We consider the hypothesis that dark matter and dark energy consists of
ultra-light self-interacting scalar particles. It is found that the
Klein-Gordon equation with only two free parameters (mass and self-coupling) on
a Schwarzschild background, at the galactic length-scales has the solution
which corresponds to Bose-Einstein condensate, behaving as dark matter, while
the constant solution at supra-galactic scales can explain dark energy.
