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. [Scene Summary] According to
Macbeth's Porter--who is still a buzzy 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.