Sleep is the most important thing when trying to lose weight. Not getting enough sleep per night-at least 6-8 hours- can lead to negative results. Sleep deprivation can lead to paranoia, your body not processing efficiently in all areas of human function as well as not healing correctly or at all when exercising.
This article written by Adam Bornstein talks about the effects of not getting enough sleep per night can have on your diet and exercise regimen.
http://www.shape.com/lifestyle/mind-and-body/why-sleep-no-1-most-important-thing-better-body