  Using the non-perturbative method of {\it dressed} states introduced in
previous publications [N.P.Andion, A.P.C. Malbouisson and A. Mattos Neto,
J.Phys.{\bf A34}, 3735, (2001); G. Flores-Hidalgo, A.P.C. Malbouisson, Y.W.
Milla, Phys. Rev. A, {\bf 65}, 063314 (2002)], we study the evolution of a
confined quantum mechanical system embedded in a {\it ohmic} environment. Our
approach furnishes a theoretical mechanism to control inhibition of the decay
of excited quantum systems in cavities, in both weak and strong coupling
regimes.
