A light sterile neutrino species has been introduced to explain simultaneously the solar and atmospheric neutrino puzzles and the results of the LSND experiment, while providing for a hot component of dark matter. Employing this scheme of neutrino masses and mixings, we show how matter-enhanced active-sterile (Formula presented) neutrino transformation followed by active-active (Formula presented) neutrino transformation can solve robustly the neutron deficit problem encountered by models of (Formula presented) nucleosynthesis associated with neutrino-heated supernova ejecta. © 2000 The American Physical Society.