Possible consequences of non-exponential behavior of the survival amplitude of an unstable particle at very late times are considered. We describe a new quantum phenomenon: Analyzing the transition time region between exponential and post-exponential form of the survival amplitude we find that the instantaneous energy of the considered unstable state can take large values, much larger than the energy of this state for t from the exponential time region. We find also that the instantaneous energy of the unstable state tends to the minimal energy of the system min E as ∞ → t which is much smaller than the energy of this state for t of the order of the lifetime of the considered state. Taking into account the results obtained for the model considered, it is hypothesized that this purely quantum mechanical effect may be responsible for the properties of broad resonances such as σ meson as well as having astrophysical consequences.