  From recent large observing campaigns, one finds that nearly all non- or
weakly magnetic cataclysmic variables in the orbital period range between 2.8
and 4 hours are of SW Sex type and as such experience very high mass transfer
rates. The evolution of cataclysmic variables as for any interacting binary is
driven by angular momentum loss which results in a decrease of the orbital
period on evolutionary time scales. In particular, all long-period systems need
to cross the SW Sex regime of the orbital period distribution before entering
the period gap. This makes the SW Sex phenomenon an evolutionary stage in the
life of a cataclysmic variable. Here, I present a short overview of the current
state of research on these systems.
