  We have investigated the compositions of hot and dense nuclear matter with
the focus on the quantum-statistical effects for light clusters. Our main
observation is that the formation of heavy nuclei in stellar matter leads to
the reduction of the number densities of light clusters. As a result, the
quantum statistical effects such as Bose-Einstein condensation of deuterons and
$\alpha$-particles are suppressed. The deviations in number densities of light
clusters between Boltzmann and quantum statistics at sub-nuclear densities and
temperatures 1-3 MeV are $\sim$0.2$\%$ at most. The condensation of
$\alpha$-particles in iso-symmetric nuclear matter is predicted only under the
assumptions that it is composed only of nucleons and light clusters and no
heavy nuclei are present. We also found that the Coulomb screening effects
hardly affect the critical baryon densities for alpha condensation, although
mass and chemical potential of $\alpha$-particles are modified.
