Recently,　Mao　(2013)　discusses　the　mean-square　exponential　stabilization　of　continuous-time　hybrid　stochastic　differential　equations　by　feedback　controls　based　on　discrete-time　state　observations.　Mao　(2013)　also　obtains　an　upper　bound　on　the　duration　tau　between　two　consecutive　state　observations.　However,　it　is　due　to　the　general　technique　used　there　that　the　bound　on　tau　is　not　very　sharp.　In　this　paper,　we　will　consider　a　couple　of　important　classes　of　hybrid　SDEs.　Making　full　use　of　their　special　features,　we　will　be　able　to　establish　a　better　bound　on　tau.　Our　new　theory　enables　us　to　observe　the　system　state　less　frequently　(so　costs　less)　but　still　to　be　able　to　design　the　feedback　control　based　on　the　discrete-time　state　observations　to　stabilize　the　given　hybrid　SDEs　in　the　sense　of　mean-square　exponential　stability.　(C)　2014　The　Authors.　Published　by　Elsevier　B.V.