  The long time diffusive behaviour of intrinsic localised modes (discrete
breathers) in the discrete damped-driven sine-Gordon chain under Gaussian white
noise (to simulate temperature) is studied. We present a theoretical model for
an approximate description of the diffusion, derive an expression for the
diffusion constant and compare with results from simulations. It turns out that
an increase of the temperature inhibits the diffusive motion in such a way that
the breather, propagating with a well-defined velocity in the noise-free case,
is almost pinned. As all physical processes in the real world occur at
temperatures T > 0, these results also have a bearing on the experimental
detection of mobile breathers, e.g. in parallel arrays of Josephson junctions.
