Inclusion Criteria:

• * Between 18 and 40 years of age
• * Drug free
• * Established disease-free status

Exclusion Criteria:

• 1. Dietary restrictions
• Participants must not have dietary restrictions that could systematically bias their macronutrient intake. The following will exclude participants from enrolling in the study based on their diet:
• * Participants who choose not to or cannot consume dairy products (milk, yogurt, cheese, ice cream)
• 2. Body Composition
• A body mass index (BMI) of 18.5\< \[BMI\] \< 25 kg/m2 and a waist circumference \<94/80cm.
• 3. Psychiatric/psychological suitability
• Each participant will undergo a structured interview (Mini International Neuropsychiatric Interview) with a qualified OHSU physician. This physician will supervise the administration and scoring of a Beck Depression Inventory II (BDI-II) questionnaire for each potential participant. The following will exclude individuals from participating based on their psychiatric or psychological evaluation:
• * Individuals with evidence of psychopathology on the BDI-II, or in a structured clinical interview with the physician
• * A history of severe psychiatric illnesses
• * Alcoholism
• * Drug dependency
• * Major depression
• * Manic depressive illness
• * Schizophrenic disorders
• * Panic disorder
• * Generalized anxiety disorder
• * Post-traumatic stress disorder
• * Agoraphobia
• * Claustrophobia
• * Paranoid personality disorder
• * Schizoid personality disorder
• * Schizotypal personality disorder
• * Borderline personality disorder
• * Antisocial personality disorder.
• * History of using antidepressant medication
• * History of using neuroleptic medication
• * History of using tranquilizers
• 4. Drug/alcohol use
• Volunteers must be drug-free (including caffeine, nicotine, alcohol and herbal medications) for the entire duration of the outpatient and in-laboratory study period, with no history of drug or alcohol dependency. All participants must be:
• * Current non-smokers, and are required to have a history of less than 5 'pack years' of smoking
• 5. Medication/drug use
• Volunteers must not be taking any prescribed medications or over the counter medications, with an exception for birth control.
• 6. Prior shift work
• For stability of endogenous circadian rhythmicity, volunteers must have no history of the following 1 year prior to the study:
• * Working irregular day and night hours
• * Regular night work
• * Rotating shift work f
• * Not have traveled more than 1 time zone during 3 months prior to the study
• 7. Chronobiologic and sleep disorders
• * Hypernychthemeral sleep/wake cycle
• * Delayed sleep phase syndrome (wake time \> 2 hours later than desired or habitually after 10:00 AM)
• * Advanced sleep phase syndrome (wake time \> 2 h earlier than desired or habitually before 5:00 AM)
• * Narcolepsy
• * Sleep apnea (apnea index \>15)
• * Insomnia (sleep complaint by history or polygraphically recorded sleep efficiency \< 80%)
• * Hypersomnia
• * Periodic Limb Movement (PLMS) (PLMS index \>15)
• * Nocturnal Paroxysmal Dystonia
• * REM-sleep behavior disorder
• * Nocturnal Enuresis; (self-report and first night in the laboratory)
• * Obstructive sleep apnea (apnea/hypopnea index \>5/h as determined by at-home monitoring)
• * The investigators will also exclude individuals with extreme chronotype using the Horne-Ostberg Morningness/Eveningness questionnaire (i.e., the Owl/Lark Questionnaire)
• 8. Diseases of the Cardiovascular System
• * Hypertension (systolic blood pressure \> 140 or diastolic blood pressure \> 90)
• * Heart failure
• * Cardiomyopathy
• * Cor pulmonale
• * Ischemic heart disease
• * Valvular heart disease
• * History of heart transplantation
• * Cardiac tumors
• * Pericardial disease
• 9. Metabolic Syndrome
• Following American Heart Association cutoffs, participants who have, in addition to abdominal fat (obese exclusion criteria), two or more of these factors will be excluded from the study:
• * HDL cholesterol of less than 40 mg/dL in men or less than 50 mg/dL in women
• * Systolic blood pressure \>135 mmHg or diastolic blood pressure \>85 mmHg
• * Fasting blood glucose ≥ 100 mg/dL
• * Triglycerides ≥ 150 mg/dL
• 10. Pre-Diabetes/Diabetes
• For participants who have a fasting blood glucose level of ≥ 100 mg/dL the investigators will measure hemoglobin A1c to exclude for diabetes (HbA1c\>5.7%).
• 11. Hypertension
• An upper cut off of 140/90 mmHg during an office blood pressure measure will be used as an exclusion criterion. After 5 minutes of rest in a seated position, blood pressure will be measured 3 times, taken 1 minute apart. The average will be used to confirm eligibility criteria. Current or history of beta blocker use will also be exclusionary.
• 12. Disorders of the Respiratory System
• * Asthma
• * Cystic fibroses
• * Chronic bronchitis
• * Emphysema
• * Airway obstruction
• * Interstitial lung diseases
• * Pulmonary hypertension
• * Lung neoplasms
• * ARDS
• 13. Disorders of the Kidney and Urinary Tract
• * Acute or chronic renal failure
• * History of renal transplantation
• * Tubulointerstitial diseases of the kidney
• * Urinary tract obstruction
• * Tumors of the urinary tract
• 14. Infectious Diseases
• * Infective endocarditis
• * HIV infection
• * Sexually transmitted diseases \[e.g., syphilis (including congenital syphilis and its sequelae), gonorrhea\],
• * Urinary tract infection
• * Osteomyelitis
• * Brucellosis
• * Toxoplasmosis,
• * Tuberculosis
• * Leptospirosis
• * Lyme disease
• * Mononucleosis
• * Hepatitis
• * Parasitic infections such as malaria, toxoplasmosis, giardiasis, schistosomiasis, leishmaniasis
• 15. Disorders of the Gastrointestinal System
• * Esophagitis
• * Peptic ulcer and gastritis
• * Neoplasms of the esophagus, stomach or bowel
• * Disorders of absorption
• * Inflammatory bowel disease
• * Diseases of the small and large intestine
• * Acute appendicitis
• * Cirrhosis or neoplasms of the liver
• * History of liver transplantation
• * Diseases of the gallbladder and bile ducts
• * Pancreatic disease
• 16. Disorders of the Immune System, Connective Tissue and Joints
• * AIDS
• * Systemic lupus erythematosus
• * Rheumatoid arthritis
• * Scleroderma
• * Ankylosing spondylitis
• * Vasculitis
• * Sarcoidosis
• 17. Disorders of the Hematopoietic System
• * Anemia
• * Leukemia
• * Myeloproliferative diseases
• * History of bone marrow transplantation
• 18. Neoplastic Diseases
• * Lymphoma
• * Carcinoma
• * Melanoma
• * Any other neoplastic diseases
• 19. Endocrine and Metabolic Diseases
• * Thyroid disease
• * Addison's Disease
• * Cushing's Syndrome
• * Aldosteronism
• * Hypoaldosteronism
• * Pheochromocytoma
• * Disorders of sexual differentiation that require hormone supplementation that may alter body weight
• * Disorders of neuroendocrine regulation
• * Diseases of the anterior pituitary and hypothalamus
• * Hemochromatosis porphyria
• * Wilson's Disease
• * Glycogen storage diseases
• * Diseases of the parathyroid gland
• * Metabolic bone disease
• * Disorders of phosphorus or magnesium metabolism
• * Paget's Disease
• 20. Neurologic Disorders
• * Epilepsy and disorders of consciousness
• * Dementia
• * Amnesic disorders
• * Neoplastic diseases of the central nervous system
• * Demyelinating diseases
• * Parkinson's Disease
• * Muscular dystrophy
• * Myasthenia gravis
• * Periodic paralysis
• * Dermatomyositis
• * Polymyositis
• * Infections of the nervous system
• * Stroke
• * History of transient ischemic attacks
• * Hydrocephalus
• * Tumors of the pituitary gland
• * Pinealoma
• * Intervertebral disc disease
• * Ataxia
• * Gilles de la Tourette Syndrome
• * Huntington's Disease
• * Tardive dyskinesia
• * History of recurrent migraine headaches
• * Neuromuscular disease.
• 21. Subjects must not be currently participating in another research study that would influence their safe participation in our study. Subjects must not be participating in a research study in which they do the following:
• * Ingest experimental medication
• * Give blood samples