  We study a composite quantum quench of the energy gap and the interactions in
the interacting \phi^4 model using a self-consistent approximation. Firstly we
review the results for free theories where a quantum quench of the energy gap
or mass leads for long times to stationary behaviour with thermal
characteristics. An exception to this rule is the 2d case with zero mass after
the quench. In the composite quench however we find that the effect of the
interactions in our approximation is simply to effectively change the value of
the mass. This means on the one hand that the interacting model also exhibits
the same stationary behaviour and on the other hand that this is now true even
for the massless 2d case.
