Ok, as soon as I saw it I thought September 11...
Personally, i feel it is obvious..
firstly.. it is observations of the year 2001...
and then it talks of war..
no war occured... it was peaceful until the "sudden" change of Sept 11 and we cannot take peace for granted..
the "sleep alone" is referring to the loss of loved ones...
the technique i figured is that the composer cleverly familiarises the responder with a well known topic that touched on everyone's emotions. Therefore pretty much having a deeper impact in representing change...
also i wasn't too sure coz none of my mates believed me and i felt like a dumbass, i checked the poet on the net and he has lived in new york previously...