Presumably, she feels disappointed and embarrassed by her husband's behavior. As the party was breaking up, Lady Macbeth chastises her husband, saying, "You have displaced the mirth, broke the good meeting / With most admired disorder" (3.4.132-133). She's been humiliated by what she perceives as her husband's cowardly behavior in regards to the presence of Banquo's ghost (of which she and the rest of their guests are insensible).
Lady Macbeth believes that Macbeth thinks he is seeing Duncan's ghost, and she says that Macbeth has been "unmanned in folly," and she yells at him, "Fie, for shame!" (3.4.88, 3.4.90). She hastily dismisses their dinner guests, both, it seems, to prevent them from seeing more of Macbeth's odd and guilty-seeming behavior as well as because she is so exhausted from the effort of keeping up appearances. When they are all gone, her answers to Macbeth's questions are short, even clipped. Perhaps she is angry with him, disappointed in him certainly. He goes on and on, and she simply tells him, "You lack the season of all natures, sleep" (3.4.173). However, from her sleepwalking in Act 5, scene 1, it looks as though it may be Lady Macbeth who lacks sleep; she is clearly not sleeping peacefully anymore.