In any event, the use of beats and pauses in dialogue is considered archaic and shouldn’t be used in a spec script. Doing so tells the actor that he should stand there and do nothing, and actors hate to be told how they should act. Just write the dialogue and let the actors figure for themselves how to say it.

Of course there are ways to imply pauses. For example, the above dialogue could have been written like this:

JIM

I’m tired.

Jim yawns.

JIM

You should get some rest too.

JANE

I’m fine.

Jim starts to stand, then passes out at Jane’s feet. He snores loudly.

JANE

But if you really want me to leave…

Here the dialogue is broken up by action. A pause is implied, but the actors are happy because they are given something to do rather than stand around waiting for their next line. It makes the scene more interesting.

hope this helps!

A BEAT helps give direction to whoever is reading the script as to the pacing and delivery of the line — but might not actually be very long or pronounced in the delivery.

A PAUSE is longer, a more pronounced break in speech.

But it’s really writer’s discretion. (The director and actors will do what they want, anyway!)