- use of any prescription medication that can affect sleep or metabolism with the exception of antihypertensive and lipid lowering agents as follows. Subjects who are taking anti-hypertensive medication and/or lipid-lowering agents will be included only if they are well controlled and on a stable regimen (no change in medications in the previous 3 months). However, beta-blockers and thiazide diuretics will not be allowed, as these medications are known to affect insulin sensitivity. Women will be required to not be on hormone replacement therapy.