On the night that Macbeth murders King Duncan, Banquo says to his son, "A heavy summons lies like lead upon me, / And yet I would not sleep: merciful powers, / Restrain in me the cursed thoughts that nature / Gives way to in repose! (2.1.6-9). Banquo doesn't say just what thoughts are disturbing his sleep, but we can guess that they have to do with the witches' prophecies. A little later in the scene, Macbeth seems to suggest that he could reward Banquo if Banquo would somehow support him in something having to do with the witches' prophecies. Banquo shows that he is suspicious of Macbeth's motives, and Macbeth ends the conversation by wishing Banquo "Good repose" (2.1.29), a good night's sleep.
After Banquo has gone to bed, Macbeth hallucinates, seeing a bloody dagger in the air, and then he tells himself that it is the time of night for such a hallucination: "Now o'er the one half-world / Nature seems dead, and wicked dreams abuse / The curtain'd sleep" (2.1.49-51). Sleep is "curtain'd" because the well-to-do used four-poster beds hung with curtains to keep out drafts. But in the dark of night wicked dreams can penetrate the curtains and sleep itself.
After Macbeth murders King Duncan, he's so unnerved that he can't move. Staring at his bloody hands, he tells his wife that as he left the King's chamber, he heard two men in another room: "There's one did laugh in's sleep, and one cried 'Murder!'" (2.2.20). To him, it's as though those men, even in their sleep, could see his bloody murderer's hands.
Moments later, still talking about the frightening things that happened to him, Macbeth tells Lady Macbeth that he thought he heard a voice telling him that he would never sleep again. The speech is one of the most famous in Macbeth :
Methought I heard a voice cry "Sleep no more!A "ravell'd sleave" is a tangled skein of thread or yarn. Macbeth uses it as a metaphor for the kind of frustration we experience when we have so many problems that we can't see the end to any of them. In such a case, we often say that we want to "sleep on it" in order to get everything straight. Macbeth also compares sleep to a soothing bath after a day of hard work, and to the main course of a feast. To Macbeth, sleep is not only a necessity of life, but something that makes life worth living, and he feels that when he murdered his King in his sleep, he murdered sleep itself.
Macbeth does murder sleep," the innocent sleep,
Sleep that knits up the ravell'd sleave of care,
The death of each day's life, sore labour's bath,
Balm of hurt minds, great nature's second course,
Chief nourisher in life's feast. (2.2.32-37)
According to Macbeth's Porter--who is still buzzed from a night of partying--sleep is one of the side effects of drink, which causes "nose-painting, sleep, and urine" (2.3.28-29). The Porter also equates sleep with impossible dreams. He says that drink makes a man horny but unable to do anything about it, so that he can only dream of having sex: Drink "equivocates him in a sleep, and, giving him the lie, leaves him. (2.3.35-36).
Later in the same scene, after Macduff has discovered the bloody body of King Duncan, he calls upon Banquo and the King's sons to awake, to "Shake off this downy sleep, death's counterfeit, / And look on death itself!" (2.3.76-77). Macduff means that although sleep and death may look similar, real sleep is "downy" and comforting, while real death is a horror.
When Macduff rings an alarm bell, Lady Macbeth enters, asking "What's the business, / That such a hideous trumpet calls to parley / The sleepers of the house?" (2.3.81-83). Her words should remind us that most of the people on stage look as if they have just been awakened from deep sleep. Macbeth and Lady Macbeth certainly appear in their nightclothes, because they want everyone to think they've been sleeping. In addition, the rest of those who are sleeping in Macbeth's castle -- Banquo, Malcolm, Donalbain, and Ross -- must appear in their nightclothes, too. This is clearly implied when Banquo proposes that they hold a meeting, "when we have our naked frailties hid, / That suffer in exposure" (2.3.126-127).
Macbeth has indeed murdered sleep.
Just after he sends the two murderers out to kill Banquo, we see that Macbeth can sleep no more. He tells his wife that he will tear the world apart rather than continue to "eat our meal in fear and sleep / In the affliction of these terrible dreams / That shake us nightly" (3.2.17-19). He goes on to say that it would better to be dead than "on the torture of the mind to lie / In restless ecstasy. Duncan is in his grave; / After life's fitful fever he sleeps well" (3.2.23). Here, "ecstasy" doesn't mean pleasure of any kind. The word refers to a sense of leaving the body, such as we often mean when we say that someone "loses it." Macbeth has terrible dreams, can't sleep, and feels like he's going crazy.
Moments later in the same scene, Macbeth boasts that a terrible deed will be done before nightfall, or -- in Shakespeare's words -- before "to black Hecate's summons / The shard-borne beetle with his drowsy hums / Hath rung night's yawning peal" (3.2.41-43). The beetle is "shard-borne" because it flies on scaly wings, and the hum of its flight is "night's yawning peal," the sound of night that tells us that it's time to sleep. But in Macbeth's mind it's also a time for death and black magic, because the beetle is answering the call of Hecate, who dwells in the underworld and is the protectress of witches.
At the end of the scene in which the Ghost of Banquo is an uninvited guest at Macbeth's banquet, Lady Macbeth says to her husband, "You lack the season of all natures, sleep" (3.4.140). A "season" in this sense is a preservative, and "natures" are different varieties of human nature. She is saying that without sleep anyone will go crazy, and Macbeth hasn't been getting his sleep. Earlier in the scene she had accused her husband of being unmanly, but now she's willing to attribute his strange behavior to a lack of sleep.
After he comes to understand that Macbeth is a murderous tyrant, Lennox learns from another Scottish Lord that Macduff has gone to the English court to ask for help. Macduff wants to overthrow Macbeth, so that King Duncan's son, Malcolm, can be King of Scotland. Once that is done, the Scottish Lord says, Scotland will enjoy the blessing of peace, so that "we may again / Give to our tables meat, sleep to our nights / Free from our feasts and banquets bloody knives" (3.6.33-35).
When he is told that he must beware Macduff, Macbeth swears that Macduff "shalt not live; / That I may tell pale-hearted fear it lies / And sleep in spite of thunder" (4.1.83-86). Thunder represents vengeance for the murders he has committed. Because of his fear of that vengeance, he has not been able to sleep, but now he thinks that one more murder will fix everything.
In the scene in which Lady Macbeth sleepwalks, her waiting gentlewoman explains to a doctor that she has seen the lady "rise from her bed, throw her night-gown upon her, unlock her closet, take forth paper, fold it, write upon't, read it, afterwards seal it, and again return to bed; yet all this while in a most fast sleep" (5.1.5-7). The doctor comments, "A great perturbation in nature, to receive at once the benefit of sleep, and do the effects of watching!" (5.1.8-10). The doctor simply means that the lady must be very troubled to act as though she is awake while she sleeps, but it's a significant observation. Lady Macbeth is not getting any sleep while she sleeps. Instead she relives the horrors of King Duncan's murder and of the visit of Banquo's ghost. "Macbeth does murder sleep," a voice cried out to Macbeth as he was about to kill King Duncan. The voice was right.
As Macbeth is putting on his armor to do battle with the English army, he asks the doctor about his wife. The doctor tells him that she is "Not so sick, my lord, / As she is troubled with thick coming fancies, / That keep her from her rest" (5.3.36-39).