I'm working on a one act play and I'm struggling to decide when a scene ends and a new one begins. Should a scene end when the location/time changes or maybe when the characters leave and new characters enter? One example I'm struggling with is a dream sequence, when the character wakes up should that be a different scene or the same scene as the dream sequence?
The dream sequence is in a different location (real or imagined), right? Unless your character dreams about being in bed, and even then I imagine it's a strikingly different scenario to the one they wake up in...
I can imagine waking up from a dream being somewhat harder to stage effectively than a simple TV cut/fade/dissolve.
Ultimately, does this particular writing detail matter much if your script is well-written and not glaringly amateurishly put together? Probably not.
Beware having too many scenes in a one-act. Because one-acts are fairly short, it can be quite annoying for the audience if there are too many lighting/scene changes. And it goes without saying you can't have backstage folk constantly moving furniture around, so mainly you have to use lighting and different stage areas. Sorry if you already know all that.
I'd say when the location changes, you're definitely into a different scene. Think how you intend to do this - are you going to move the actors (or introduce new ones) to a different stage area and use a light fade or snap black-out to end the first scene, then a fade up into the second?
Presumably the person waking up is both part of the dream sequence and part of the waking up, so you'd need to move him elsewhere(if there's a bed involved).
Could you try to get hold of a couple of scripts of plays you've maybe seen that do the kind of thing you're trying for?