  Time-energy uncertainty relation (TEUR) plays a fundamental role in quantum
mechanics, as it allows to grasp peculiar aspects of a variety of phenomena
based on very general principles and symmetries of the theory. Using the
Mandelstam-Tamm method, TEUR has been recently derived for neutrino
oscillations by connecting the uncertainty on neutrino energy with the
characteristic time-scale of oscillations. Interestingly enough, the suggestive
interpretation of neutrinos as unstable-like particles has proved to naturally
emerge in this context. Further aspects have been later discussed in
semiclassical gravity by computing corrections to the neutrino energy
uncertainty in a generic stationary curved spacetime, and in quantum field
theory, where the clock observable turns out to be identified with the
non-conserved flavor charge operator. In the present work, we give an overview
on the above achievements. In particular, we analyze the implications of TEUR
and explore the impact of gravitational and non-relativistic effects on the
standard condition for neutrino oscillations.
