You may be able to get along well with your daily routine with just five or six hours of sleep. But, to ensure optimum fat loss and good health, you have to get atleast eight hours of sleep every night. Adequate sleep controls the hormones that regulate your appetite. Researchers from the University of Chicago say that six days of reduced sleep decreased glucose tolerance and insulin response by 30 per cent. In simple terms, this means lack of sufficient sleep reduces the body's ability to process sugar efficiently, which increases the chances of gaining more body fat. So, if you are unable to get eight hours of continuous sleep at night, try to compensate by taking a nap during the day.