  Vacuum decay in de Sitter space is a process of great physical interest, as
it allows to rule out cosmological models in the early and current Universe.
Its rate may be described in terms of an instanton in Euclidean space called
bounce and it is usually interpreted as thermally assisted quantum tunneling.
According to analytical and numerical evidence in the literature, a bounce
exists only for certain values of the Hubble parameter in single scalar field
theories with Einstein-Hilbert gravity. In the present paper, we rely on a
novel approach to provide more stringent bounds, which may be easily extended
to theories with non-minimally coupled and quadratic gravity. An additional
restriction is also derived, which specifically applies to the latter.
