  We present the results of the first theoretical non-radial non-adiabatic
pulsational study of M dwarf stellar models with masses in the range 0.1 to
0.5M_solar. We find the fundamental radial mode to be unstable due to an
\epsilon mechanism caused by deuterium (D-) burning for the young 0.1 and
0.2M_solar models, by non-equilibrium He^3 burning for the 0.2 and 0.25M_solar
models of 10^4Myr, and by a flux blocking mechanism for the partially
convective 0.4 and 0.5M_solar models once they reach the age of 500Myr. The
periods of the overstable modes excited by the D-burning are in the range 4.2
to 5.2h for the 0.1M_solar models and is of order 8.4h for the 0.2M_solar
models. The periods of the modes excited by He^3 burning and flux blocking are
in the range 23 to 40min. The more massive and oldest models are more promising
for the observational detection of pulsations, as their ratio of instability
e-folding time to age is more favourable.
