By night Lou stalks the streets of L.A. looking for potential video footage. By day he, by his own admission, spends his time on the internet, learning whatever can help him in his journey. Between all that, there's little time for him to sleep, something we never actually see him do in the film. Living in a studio apartment with seemingly no space for a bed and busy at both day and night, there's a real purpose in showing him never hitting the hay, helping further his unfaltering drive and the unnerving nature of his character. It's one of the more abstract elements of a film that is for the most part pretty naturalistic. This doesn't add much to the film as whole by itself, but plays into some of the things we'll be looking at in a minute. Due to the shooting schedule (and no doubt a bit of effort put into characterisation) Gyllenhaal himself didn't sleep much during the shooting of the film, helping further Lou's gaunt look (which was primarily achieved by losing a good amount of weight).
