  We investigate the use of hybrid equations of state in binary neutron-star
simulations in full general relativity, where thermal effects are included in
an approximate way through the adiabatic index $\Gamma_{\rm{th}}$. We employ a
newly developed finite-temperature equation of state derived in the
Brueckner-Hartree-Fock approach and carry out comparisons with the
corresponding hybrid versions of the same equation of state, investigating how
different choices of $\Gamma_{\rm{th}}$ affect the gravitational-wave signal
and the hydrodynamical properties of the remnant. We also perform comparisons
with the widely used SFHo equation of state, detailing the differences between
the two cases. Overall, we determine that when using a hybrid equation of state
in binary neutron-star simulations, the value of thermal adiabatic index
$\Gamma_{\rm{th}} \approx 1.7$ best approximates the dynamical and
thermodynamical behaviour of matter computed using complete, finite-temperature
equations of state.
