I think all of the songs on Bastille's album all seem to link together with a sense of discovering who you are, for example in the Laura Palmer video, being lost in this process, like in these lyrics here, and then becoming acceptant of who you are, "Do you like the person you've become?" In Weight Of Living pt 1/2.
I think this is just about discovering yourself as an individual and going back to what you feel is comfortable, home, after trying new things. "We are the greatest pretenders," Could be trying to show how people pretend to be happy with themselves but actually can find many flaws with themselves- excuse the pun.
Perhaps the insecurities the person feels catches up to them at night, for example how someone battling depression may feel, though in the morning, they are cast out to be the normal person. They know they'll land themselves back in that position.
I think the birds could possibly be a reference to Alfred Hitchcock's film, The Birds. Whether I am saying this because Dan is an old film fanboy, or simply because I can see no other explanation for it, I don't know.