Recently,　Mao　[Automatica　J.　IFAC,　49　(2013),　pp.　3677-3681]　initiated　the　study　the　mean-square　exponential　stabilization　of　continuous-time　hybrid　stochastic　differential　equations　by　feedback　controls　based　on　discrete-time　state　observations.　In　the　same　paper　Mao　also　obtains　an　upper　bound　on　the　duration　t　between　two　consecutive　state　observations.　However,　it　is　due　to　the　general　technique　used　there　that　the　bound　on　t　is　not　very　sharp.　In　this　paper,　we　will　be　able　to　establish　a　better　bound　on　t　making　use　of　Lyapunov　functionals.　We　will　discuss　the　stabilization　not　only　in　the　sense　of　exponential　stability　(as　Mao　does　in　[Automatica　J.　IFAC,　49　(2013),　pp.　3677-3681])　but　also　in　other　sense-that　of　H∞　stability　or　asymptotic　stability.　We　will　consider　not　only　the　mean　square　stability　but　also　the　almost　sure　stability.　©　2015　Society　for　Industrial　and　Applied　Mathematics.