Yes, in a positive way! While fasting, the body must bear a tremendous load of toxins being pushed out of every single cell and into the bloodstream. The "detox" part of fasting is pretty brutal and rather flu-like, and the body will take as much sleep as it can get! For the first week or so of fasting, prepare for needing more sleep than normal because the boy will be working extra hard. However, after the initial detox has ended, your sleep cycle will be much improved. You will find you need less sleep than normal and you will wake up feeling energetic, not all fuzzy like most of us feel in the mornings. This is because the body is not stuck digesting food and cleaning itself all night. Sleep will make you more energetic.