Inclusion Criteria:  UC patients:  Inactive Disease (Mayo Score ≤ 2) Stable medications with no disease flares for the > 3 months Left-sided UC (Montreal E1 or E2) Normal psychological evaluation and negative drug screen (See Below)  Healthy Controls:  M/F, 18-40 y/o, age ± 3y sex, race, and BMI match with UC subject No clinical evidence of any medical illness Normal psychological evaluation and negative drug screen (See Below)  Exclusion Criteria:  UC patients:  Patients with other forms of colitis such as Crohn's disease (CD) or indeterminate colitis Patient with active UC (Mayo > 2) Pancolonic UC (colitis past the splenic flexure, Montreal E3)) Use of biologic or immunomodulatory medications (i.e. Infliximab, Adalimumab, azathioprine, Vedolizumab, methotrexate, etc.) Gastrointestinal surgery Other GI diseases or systemic diseases (cardiac, renal failure, cirrhosis) Shift work in the last 6 months Antibiotic use within last 12 weeks Patients who have used anti-diarrheal agents such as Lomotil or Imodium within 3 days of the study Prednisone use the last 30 days Significant Depression (score ≥ 14 BDI) Significant Anxiety (score ≥ 40 STAI) Use of probiotic supplement in last 4 weeks except yogurt. Intentional change in diet. Chronic use of NSAIDS. A washout period of 3 weeks is needed before the subject could be enrolled into the study. Low dose aspirin is allowed. Chronic Alcohol use. A washout period of 3 weeks is needed before the subject could be enrolled into the study.  Healthy Controls:  History of drug abuse, gastrointestinal (GI) surgery, GI diseases, or systemic diseases such as renal (creatinine>1.2 mg/dl), liver, cardiac, or diabetes (Hgb-A1c>8%) Antibiotic use within last 12 weeks Shift work in the last 6 months Use of probiotic supplement except yogurt in last 4 weeks. Atypical American diet with daily fiber ≥ 16 grams or daily saturated fat ≤ 11 grams by Food Frequency Questionnaire Chronic use of NSAIDS. A washout period of 3 weeks is needed before the subject could be enrolled into the study. Chronic Alcohol use. A washout period of 3 weeks is needed before the subject could be enrolled into the study. Significant Depression (score ≥ 14 BDI) Significant Anxiety (score ≥ 40 STAI) Regular use of medications that affect intestinal permeability, intestinal motility and/or endogenous melatonin including metoclopramide, NSAIDs, antibiotics, beta blocker, psychotropic medication, hypnotics and exogenous melatonin products during 4 weeks prior to the study People who crossed more than 2 time zones in the previous month Inability to sign an informed consent form.