  Context. In tight binary star systems, tidal interactions can significantly
influence the rotational and orbital evolution of both stars, and therefore
their activity evolution. This can have strong effects on the atmospheric
evolution of planets that are orbiting the two stars.
  Aims. In this paper, we aim to study the evolution of stellar rotation and of
X-ray and ultraviolet (XUV) radiation in tight binary systems consisting of two
solar mass stars and use our results to study planetary atmosphere evolution in
the habitable zones of these systems.
  Methods. We have applied a rotation model developed for single stars to
binary systems, taking into account the effects of tidal interactions on the
rotational and orbital evolution of both stars. We used empirical
rotation-activity relations to predict XUV evolution tracks for the stars,
which we used to model hydrodynamic escape of hydrogen dominated atmospheres.
  Results. When significant, tidal interactions increase the total amount of
XUV energy emitted, and in the most extreme cases by up to factor of $\sim$50.
We find that in the systems that we study, habitable zone planets with masses
of 1~M$_\oplus$ can lose huge hydrogen atmospheres due to the extended high
levels of XUV emission, and the time that is needed to lose these atmospheres
depends on the binary orbital separation.For some orbital separations, and when
the stars are born as rapid rotators, it is also possible for tidal
interactions to protect atmospheres from erosion by quickly spinning down the
stars. For very small orbital separations, the loss of orbital angular momentum
by stellar winds causes the two stars to merge. We suggest that the merging of
the two stars could cause previously frozen planets to become habitable due to
the habitable zone boundaries moving outwards.
