Inclusion Criteria:  Participants will be younger (18-45 y), healthy, non-diabetic with BMI 20-30, European/Hispanic/African-American ancestry, and without medication use (excepting oral contraceptives). Participants must be free from acute, chronic, or debilitating medical conditions.  Exclusion Criteria:  We will exclude people with reported or actigraphically measured habitual outpatient sleep durations of <5h or >9h and people who have recently (within last 6 months) taken antibiotics. major visual or auditory handicaps