Lady Macbeth is nervous and is in a heightened state, but she is able to keep her goal in mind and maintain her composure enough to help her husband regain his composure when they hear someone knocking at the gate. It is clear that she is in a heightened state in the first 30 lines or so. She and Macbeth have a quick exchange about noises heard in the castle as Macbeth killed Duncan. She regains control of herself quickly though and less than 50 lines later, she chastises her husband because he says he feels regret for what he's just done. She is the one then who takes the bloody daggers to plant them on the sleeping guards She next tells Macbeth that they must calm themselves and appear normal to whomever it is who is at the gate. She tells him to get on his nightgown and to compose himself. She appears to be in complete control, but Act 5 reveals that her composure was short-lived as she is insane by that act.
Right from the onset of Act II Scene 2 Lady macbeth is the perfect picture of composure and observation.Line 1:
That which has made them drunk has made me bold. What hath quenched them hath given me fire.
A composed mind is observant as well as analytical. Lady mMacbeth indicates both in lines 4-8:
The doors are open, and the surfeited grooms Do mock their charge with snores. I have drugged their possets,
The poor display of work ethics of the grooms does not escape Lady Macbeth as she notes 'mock their charge with their snores'. Composure causes Lady Macbeth to note how like her own father Duncan looks as he sleeps.
Line 12: Had he not resembled My father as he slept, I had done't.
While Macbeth himself is wishy-washy in his observation that 'This is a sorry sight', Lady Macbeth is composed and quick to point out to him the foolishness of that kind of thinking in Line 25: 'A foolish thought to say a sorry sight'.
While Macbeth is lost in the mental agony of replaying the Murder scene, Lady macbeth is down to earth and observes just the barest physical facts in Line 29: 'There are two lodged together'.
Throughout the rest of the scene she is the voice of composure as she counses, comforts and even, at times, commands her husband. Line 33: Consider it not so deeply Line 36: These deeds must not be thought after these ways; so it will make us mad. She even chastices her husband and ultimately takes direct control and command: Line 48: You do unbend your noble strength to think So brainsickly of things. Go get the water... Her composure seems to increase in intensity even as his decreases until, almost in sheer disgust, she seems to take total control and has to get down to doing what needs to be done herself: Line 56: Infirm of purpose! Give me the daggers. The sleeping and the dead are but pictures. 'Tis the eye of childhood that fears a painted devil.
Throughout the rest of the scene, due to her composure, the Lady Macbeth is indeed seen as the commander in chief as she issues direct orders and commands: Line 69: Retire we to our chambers Line 73: Get on your night gown Line 74: Be not lost So poorly in your thoughts.