Clinical Research Directory

* INCLUSION CRITERIA: Individuals must meet the inclusion criteria listed below in order to be eligible to participate in the study. * Males between the ages of 18 and 80 with mild to moderate active psoriasis by PASI score for inclusion in psoriasis group * Age (plus or minus 10 yrs) and BMI (plus or minus 5 kg/m\^2) matched control male subjects for inclusion in the control group. * Ability to provide informed consent * Willingness and ability to participate in study procedures EXCLUSION CRITERIA: * Severe psoriasis by PASI (Psoriasis Area and Severity Index) score \> 12 * Treatment with systemic biologic immune modifying agents within the last 2 months. * Currently on treatment for allergies or other inflammatory diseases. * Has taken Vitamin B or tryptophan supplementation within 2 weeks of participation. * Unwillingness/inability to provide informed consent. * Individuals with known history of type 1 and 2 diabetes mellitus or other metabolic conditions that would interfere with study parameters including chronic kidney disease, chronic liver disease, history of hypoglycemia * On treatment with medication that would interfere with study parameters including anti-hyperglycemic medications, systemic steroids, adrenergic-stimulating agents, other medications known to affect sleep, circadian rhythms or metabolism. * Caffeine in excess of three 8 oz cups per day. * Factors that affect circadian rhythm including individuals who perform overnight shift work, irregular sleep and/ or eating schedules, regularly fast for more than 15 hours/ day * Regular use of tobacco product within last 3 months. * Consuming more than 3 servings of alcohol/ day * Engaged in competitive sports training * Moderate to severe claustrophobia * Unstable weight with more than 5% body weight change in last 3 months * Food allergies or intolerances or dietary patterns that would prohibit consumption of the metabolic diet or mixed meal test.