  We study models in which reheating happens only through non-perturbative
processes. The energy transferred can be exponentially suppressed unless the
inflaton is coupled to a particle with a parametrically small mass.
Additionally, in some models a light scalar with a negative mass squared
parameter leads to much more efficient reheating than one with a positive mass
squared of the same magnitude. If a theory contains many sectors similar to the
Standard Model coupled to the inflaton via their Higgses, such dynamics can
realise the Nnaturalness solution to the hierarchy problem. A sector containing
a light Higgs with a non-zero vacuum expectation value is dominantly reheated
and there is little energy transferred to the other sectors, consistent with
cosmological constraints. The inflaton must decouple from other particles and
have a flat potential at large field values, in which case the visible sector
UV cutoff can be raised to 10 TeV in a simple model.
