  We investigate the tail asymptotic behavior of the sojourn time for a large
class of centered Gaussian processes $X$, in both continuous- and discrete-time
framework. All results obtained here are new for the discrete-time case. In the
continuous-time case, we complement the investigations of [1,2] for
non-stationary $X$. A by-product of our investigation is a new representation
of Pickands constant which is important for Monte-Carlo simulations and yields
a sharp lower bound for Pickands constant.
