Sleep deprivation raises cortisol and lowers testosterone in men, and sleep limitation of 3 to 4 hours per night causes insulin resistance. Researchers clamped cortisol and testosterone to see how they affected insulin resistance. This was a randomised double-blind, in-laboratory crossover trial in which 34 healthy young males were randomly assigned to one of two treatment conditions: dual hormone clamp or matched placebo. Under both treatment settings, fasting blood samples and an additional 23 samples for a 3-hour oral glucose tolerance test (OGTT) were taken before and after sleep restriction. Fasting samples were analysed for cytokines and hormones. The OGTT was used to calculate overall insulin sensitivity by integrating complementary measurements such as the homeostasis model evaluation of fasting insulin resistance, the Matsuda index of the absorptive state, and the minimum model of both fasting and absorptive states. Sleep deprivation alone resulted in hyperinsulinemia, hyperglycemia, and insulin resistance. Cortisol and testosterone suppression reduced the development of total insulin resistance and hyperinsulinemia by 50%. Interleukin-6, high-sensitivity C-reactive protein, peptide YY, and ghrelin did not alter, but tumour necrosis factor- and leptin changed in ways that would have reduced insulin resistance if sleep restriction had been used alone.
Fixing cortisol-testosterone exposure protects men from developing insulin resistance and hyperinsulinemia, but not hyperglycemia, as a result of prolonged sleep deprivation. The interaction between cortisol and testosterone may be an essential mechanism through which sleep deprivation affects metabolic health.