Restriction of sleep to four hours in healthy volunteers resulted in a 40 percent decrease in insulin sensitivity,29 even after a single sleep-deprived night.30 After five days of sleep restriction, insulin secretion increased 20 percent and insulin sensitivity decreased by 25 percent. Cortisol increased by 20 percent.31 In another study, shortened sleep duration increased the risk of type 2 diabetes.32
Lack of sleep can cause type-2 diabetes
