I agree with WY that you shouldn't worry. It's commonly held that fasters need less sleep and it's quite a common theme amongst the fasters posting on this forum.
If you're fasting for weight loss, the hygienists recommend regular but limited exercise to restrict loss of muscle tone. For healing, the ideal is to spend as much time as possible lying flat in bed resting or sleeping to allow the body to focus as much energy as possible on detox and repair.
Please don't despair. Go along for the ride and marvel at mystery of healing that you're undergoing. Your body knows what it's doing even if it cannot explain the process to you along the way.